root/ui/views/win/hwnd_message_handler.cc

DEFINITIONS

1. got_mouse_up
2. key_hook_
3. Unhook
4. MouseHook
5. KeyHook
6. EnumChildWindowsForRedraw
7. GetMonitorAndRects
8. EnableMenuItemByCommand
9. SendDwmCompositionChanged
10. ClipDCToChild
11. IsTopLevelWindow
12. AddScrollStylesToWindow
13. force_
14. ScopedRedrawLock
15. CancelUnlockOperation
16. touch_down_context_
17. Init
18. InitModalType
19. Close
20. CloseNow
21. GetWindowBoundsInScreen
22. GetClientAreaBoundsInScreen
23. GetRestoredBounds
24. GetClientAreaBounds
25. GetWindowPlacement
26. SetBounds
27. SetSize
28. CenterWindow
29. SetRegion
30. StackAbove
31. StackAtTop
32. Show
33. ShowWindowWithState
34. ShowMaximizedWithBounds
35. Hide
36. Maximize
37. Minimize
38. Restore
39. Activate
40. Deactivate
41. SetAlwaysOnTop
42. IsVisible
43. IsActive
44. IsMinimized
45. IsMaximized
46. IsAlwaysOnTop
47. RunMoveLoop
48. EndMoveLoop
49. SendFrameChanged
50. FlashFrame
51. ClearNativeFocus
52. SetCapture
53. ReleaseCapture
54. HasCapture
55. SetVisibilityChangedAnimationsEnabled
56. SetTitle
57. SetCursor
58. FrameTypeChanged
59. SchedulePaintInRect
60. SetOpacity
61. SetWindowIcons
62. DispatchKeyEventPostIME
63. GetDefaultWindowIcon
64. OnWndProc
65. HandleMouseMessage
66. HandleTouchMessage
67. HandleKeyboardMessage
68. HandleScrollMessage
69. HandleNcHitTestMessage
70. GetAppbarAutohideEdges
71. OnAppbarAutohideEdgesChanged
72. SetInitialFocus
73. PostProcessActivateMessage
74. RestoreEnabledIfNecessary
75. ExecuteSystemMenuCommand
76. TrackMouseEvents
77. ClientAreaSizeChanged
78. GetClientAreaInsets
79. ResetWindowRegion
80. UpdateDwmNcRenderingPolicy
81. DefWindowProcWithRedrawLock
82. LockUpdates
83. UnlockUpdates
84. RedrawLayeredWindowContents
85. ForceRedrawWindow
86. OnActivateApp
87. OnAppCommand
88. OnCancelMode
89. OnCaptureChanged
90. OnClose
91. OnCommand
92. OnCreate
93. OnDestroy
94. OnDisplayChange
95. OnDwmCompositionChanged
96. OnEnterMenuLoop
97. OnEnterSizeMove
98. OnEraseBkgnd
99. OnExitMenuLoop
100. OnExitSizeMove
101. OnGetMinMaxInfo
102. OnGetObject
103. OnImeMessages
104. OnInitMenu
105. OnInputLangChange
106. OnKeyEvent
107. OnKillFocus
108. OnMouseActivate
109. OnMouseRange
110. OnMove
111. OnMoving
112. OnNCActivate
113. OnNCCalcSize
114. OnNCHitTest
115. OnNCPaint
116. OnNCUAHDrawCaption
117. OnNCUAHDrawFrame
118. OnNotify
119. OnPaint
120. OnReflectedMessage
121. OnScrollMessage
122. OnSessionChange
123. OnSetCursor
124. OnSetFocus
125. OnSetIcon
126. OnSetText
127. OnSettingChange
128. OnSize
129. OnSysCommand
130. OnThemeChanged
131. OnTouchEvent
132. OnWindowPosChanging
133. OnWindowPosChanged
134. HandleTouchEvents
135. ResetTouchDownContext
136. HandleMouseEventInternal
137. IsSynthesizedMouseMessage

// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "ui/views/win/hwnd_message_handler.h"

#include <dwmapi.h>
#include <oleacc.h>
#include <shellapi.h>
#include <wtsapi32.h>
#pragma comment(lib, "wtsapi32.lib")

#include "base/bind.h"
#include "base/debug/trace_event.h"
#include "base/win/win_util.h"
#include "base/win/windows_version.h"
#include "ui/base/touch/touch_enabled.h"
#include "ui/base/view_prop.h"
#include "ui/base/win/internal_constants.h"
#include "ui/base/win/lock_state.h"
#include "ui/base/win/mouse_wheel_util.h"
#include "ui/base/win/shell.h"
#include "ui/base/win/touch_input.h"
#include "ui/events/event.h"
#include "ui/events/event_utils.h"
#include "ui/events/gestures/gesture_sequence.h"
#include "ui/events/keycodes/keyboard_code_conversion_win.h"
#include "ui/gfx/canvas.h"
#include "ui/gfx/canvas_skia_paint.h"
#include "ui/gfx/icon_util.h"
#include "ui/gfx/insets.h"
#include "ui/gfx/path.h"
#include "ui/gfx/path_win.h"
#include "ui/gfx/screen.h"
#include "ui/gfx/win/dpi.h"
#include "ui/gfx/win/hwnd_util.h"
#include "ui/native_theme/native_theme_win.h"
#include "ui/views/views_delegate.h"
#include "ui/views/widget/monitor_win.h"
#include "ui/views/widget/widget_hwnd_utils.h"
#include "ui/views/win/appbar.h"
#include "ui/views/win/fullscreen_handler.h"
#include "ui/views/win/hwnd_message_handler_delegate.h"
#include "ui/views/win/scoped_fullscreen_visibility.h"

namespace views {
namespace {

// MoveLoopMouseWatcher is used to determine if the user canceled or completed a
// move. win32 doesn't appear to offer a way to determine the result of a move,
// so we install hooks to determine if we got a mouse up and assume the move
// completed.
class MoveLoopMouseWatcher {
 public:
  MoveLoopMouseWatcher(HWNDMessageHandler* host, bool hide_on_escape);
  ~MoveLoopMouseWatcher();

  // Returns true if the mouse is up, or if we couldn't install the hook.
  bool got_mouse_up() const { return got_mouse_up_; }

 private:
  // Instance that owns the hook. We only allow one instance to hook the mouse
  // at a time.
  static MoveLoopMouseWatcher* instance_;

  // Key and mouse callbacks from the hook.
  static LRESULT CALLBACK MouseHook(int n_code, WPARAM w_param, LPARAM l_param);
  static LRESULT CALLBACK KeyHook(int n_code, WPARAM w_param, LPARAM l_param);

  void Unhook();

  // HWNDMessageHandler that created us.
  HWNDMessageHandler* host_;

  // Should the window be hidden when escape is pressed?
  const bool hide_on_escape_;

  // Did we get a mouse up?
  bool got_mouse_up_;

  // Hook identifiers.
  HHOOK mouse_hook_;
  HHOOK key_hook_;

  DISALLOW_COPY_AND_ASSIGN(MoveLoopMouseWatcher);
};

// static
MoveLoopMouseWatcher* MoveLoopMouseWatcher::instance_ = NULL;

MoveLoopMouseWatcher::MoveLoopMouseWatcher(HWNDMessageHandler* host,
                                           bool hide_on_escape)
    : host_(host),
      hide_on_escape_(hide_on_escape),
      got_mouse_up_(false),
      mouse_hook_(NULL),
      key_hook_(NULL) {
  // Only one instance can be active at a time.
  if (instance_)
    instance_->Unhook();

  mouse_hook_ = SetWindowsHookEx(
      WH_MOUSE, &MouseHook, NULL, GetCurrentThreadId());
  if (mouse_hook_) {
    instance_ = this;
    // We don't care if setting the key hook succeeded.
    key_hook_ = SetWindowsHookEx(
        WH_KEYBOARD, &KeyHook, NULL, GetCurrentThreadId());
  }
  if (instance_ != this) {
    // Failed installation. Assume we got a mouse up in this case, otherwise
    // we'll think all drags were canceled.
    got_mouse_up_ = true;
  }
}

MoveLoopMouseWatcher::~MoveLoopMouseWatcher() {
  Unhook();
}

void MoveLoopMouseWatcher::Unhook() {
  if (instance_ != this)
    return;

  DCHECK(mouse_hook_);
  UnhookWindowsHookEx(mouse_hook_);
  if (key_hook_)
    UnhookWindowsHookEx(key_hook_);
  key_hook_ = NULL;
  mouse_hook_ = NULL;
  instance_ = NULL;
}

// static
LRESULT CALLBACK MoveLoopMouseWatcher::MouseHook(int n_code,
                                                 WPARAM w_param,
                                                 LPARAM l_param) {
  DCHECK(instance_);
  if (n_code == HC_ACTION && w_param == WM_LBUTTONUP)
    instance_->got_mouse_up_ = true;
  return CallNextHookEx(instance_->mouse_hook_, n_code, w_param, l_param);
}

// static
LRESULT CALLBACK MoveLoopMouseWatcher::KeyHook(int n_code,
                                               WPARAM w_param,
                                               LPARAM l_param) {
  if (n_code == HC_ACTION && w_param == VK_ESCAPE) {
    if (base::win::GetVersion() >= base::win::VERSION_VISTA) {
      int value = TRUE;
      HRESULT result = DwmSetWindowAttribute(
          instance_->host_->hwnd(),
          DWMWA_TRANSITIONS_FORCEDISABLED,
          &value,
          sizeof(value));
    }
    if (instance_->hide_on_escape_)
      instance_->host_->Hide();
  }
  return CallNextHookEx(instance_->key_hook_, n_code, w_param, l_param);
}

// Called from OnNCActivate.
BOOL CALLBACK EnumChildWindowsForRedraw(HWND hwnd, LPARAM lparam) {
  DWORD process_id;
  GetWindowThreadProcessId(hwnd, &process_id);
  int flags = RDW_INVALIDATE | RDW_NOCHILDREN | RDW_FRAME;
  if (process_id == GetCurrentProcessId())
    flags |= RDW_UPDATENOW;
  RedrawWindow(hwnd, NULL, NULL, flags);
  return TRUE;
}

bool GetMonitorAndRects(const RECT& rect,
                        HMONITOR* monitor,
                        gfx::Rect* monitor_rect,
                        gfx::Rect* work_area) {
  DCHECK(monitor);
  DCHECK(monitor_rect);
  DCHECK(work_area);
  *monitor = MonitorFromRect(&rect, MONITOR_DEFAULTTONULL);
  if (!*monitor)
    return false;
  MONITORINFO monitor_info = { 0 };
  monitor_info.cbSize = sizeof(monitor_info);
  GetMonitorInfo(*monitor, &monitor_info);
  *monitor_rect = gfx::Rect(monitor_info.rcMonitor);
  *work_area = gfx::Rect(monitor_info.rcWork);
  return true;
}

struct FindOwnedWindowsData {
  HWND window;
  std::vector<Widget*> owned_widgets;
};

// Enables or disables the menu item for the specified command and menu.
void EnableMenuItemByCommand(HMENU menu, UINT command, bool enabled) {
  UINT flags = MF_BYCOMMAND | (enabled ? MF_ENABLED : MF_DISABLED | MF_GRAYED);
  EnableMenuItem(menu, command, flags);
}

// Callback used to notify child windows that the top level window received a
// DWMCompositionChanged message.
BOOL CALLBACK SendDwmCompositionChanged(HWND window, LPARAM param) {
  SendMessage(window, WM_DWMCOMPOSITIONCHANGED, 0, 0);
  return TRUE;
}

// See comments in OnNCPaint() for details of this struct.
struct ClipState {
  // The window being painted.
  HWND parent;

  // DC painting to.
  HDC dc;

  // Origin of the window in terms of the screen.
  int x;
  int y;
};

// See comments in OnNCPaint() for details of this function.
static BOOL CALLBACK ClipDCToChild(HWND window, LPARAM param) {
  ClipState* clip_state = reinterpret_cast<ClipState*>(param);
  if (GetParent(window) == clip_state->parent && IsWindowVisible(window)) {
    RECT bounds;
    GetWindowRect(window, &bounds);
    ExcludeClipRect(clip_state->dc,
      bounds.left - clip_state->x,
      bounds.top - clip_state->y,
      bounds.right - clip_state->x,
      bounds.bottom - clip_state->y);
  }
  return TRUE;
}

// The thickness of an auto-hide taskbar in pixels.
const int kAutoHideTaskbarThicknessPx = 2;

bool IsTopLevelWindow(HWND window) {
  long style = ::GetWindowLong(window, GWL_STYLE);
  if (!(style & WS_CHILD))
    return true;
  HWND parent = ::GetParent(window);
  return !parent || (parent == ::GetDesktopWindow());
}

void AddScrollStylesToWindow(HWND window) {
  if (::IsWindow(window)) {
    long current_style = ::GetWindowLong(window, GWL_STYLE);
    ::SetWindowLong(window, GWL_STYLE,
                    current_style | WS_VSCROLL | WS_HSCROLL);
  }
}

const int kTouchDownContextResetTimeout = 500;

// Windows does not flag synthesized mouse messages from touch in all cases.
// This causes us grief as we don't want to process touch and mouse messages
// concurrently. Hack as per msdn is to check if the time difference between
// the touch message and the mouse move is within 500 ms and at the same
// location as the cursor.
const int kSynthesizedMouseTouchMessagesTimeDifference = 500;

}  // namespace

// A scoping class that prevents a window from being able to redraw in response
// to invalidations that may occur within it for the lifetime of the object.
//
// Why would we want such a thing? Well, it turns out Windows has some
// "unorthodox" behavior when it comes to painting its non-client areas.
// Occasionally, Windows will paint portions of the default non-client area
// right over the top of the custom frame. This is not simply fixed by handling
// WM_NCPAINT/WM_PAINT, with some investigation it turns out that this
// rendering is being done *inside* the default implementation of some message
// handlers and functions:
//  . WM_SETTEXT
//  . WM_SETICON
//  . WM_NCLBUTTONDOWN
//  . EnableMenuItem, called from our WM_INITMENU handler
// The solution is to handle these messages and call DefWindowProc ourselves,
// but prevent the window from being able to update itself for the duration of
// the call. We do this with this class, which automatically calls its
// associated Window's lock and unlock functions as it is created and destroyed.
// See documentation in those methods for the technique used.
//
// The lock only has an effect if the window was visible upon lock creation, as
// it doesn't guard against direct visiblility changes, and multiple locks may
// exist simultaneously to handle certain nested Windows messages.
//
// IMPORTANT: Do not use this scoping object for large scopes or periods of
//            time! IT WILL PREVENT THE WINDOW FROM BEING REDRAWN! (duh).
//
// I would love to hear Raymond Chen's explanation for all this. And maybe a
// list of other messages that this applies to ;-)
class HWNDMessageHandler::ScopedRedrawLock {
 public:
  explicit ScopedRedrawLock(HWNDMessageHandler* owner)
    : owner_(owner),
      hwnd_(owner_->hwnd()),
      was_visible_(owner_->IsVisible()),
      cancel_unlock_(false),
      force_(!(GetWindowLong(hwnd_, GWL_STYLE) & WS_CAPTION)) {
    if (was_visible_ && ::IsWindow(hwnd_))
      owner_->LockUpdates(force_);
  }

  ~ScopedRedrawLock() {
    if (!cancel_unlock_ && was_visible_ && ::IsWindow(hwnd_))
      owner_->UnlockUpdates(force_);
  }

  // Cancel the unlock operation, call this if the Widget is being destroyed.
  void CancelUnlockOperation() { cancel_unlock_ = true; }

 private:
  // The owner having its style changed.
  HWNDMessageHandler* owner_;
  // The owner's HWND, cached to avoid action after window destruction.
  HWND hwnd_;
  // Records the HWND visibility at the time of creation.
  bool was_visible_;
  // A flag indicating that the unlock operation was canceled.
  bool cancel_unlock_;
  // If true, perform the redraw lock regardless of Aero state.
  bool force_;

  DISALLOW_COPY_AND_ASSIGN(ScopedRedrawLock);
};

////////////////////////////////////////////////////////////////////////////////
// HWNDMessageHandler, public:

long HWNDMessageHandler::last_touch_message_time_ = 0;

HWNDMessageHandler::HWNDMessageHandler(HWNDMessageHandlerDelegate* delegate)
    : delegate_(delegate),
      fullscreen_handler_(new FullscreenHandler),
      weak_factory_(this),
      waiting_for_close_now_(false),
      remove_standard_frame_(false),
      use_system_default_icon_(false),
      restore_focus_when_enabled_(false),
      restored_enabled_(false),
      current_cursor_(NULL),
      previous_cursor_(NULL),
      active_mouse_tracking_flags_(0),
      is_right_mouse_pressed_on_caption_(false),
      lock_updates_count_(0),
      ignore_window_pos_changes_(false),
      last_monitor_(NULL),
      use_layered_buffer_(false),
      layered_alpha_(255),
      waiting_for_redraw_layered_window_contents_(false),
      is_first_nccalc_(true),
      menu_depth_(0),
      autohide_factory_(this),
      id_generator_(0),
      needs_scroll_styles_(false),
      in_size_loop_(false),
      touch_down_context_(false) {
}

HWNDMessageHandler::~HWNDMessageHandler() {
  delegate_ = NULL;
  // Prevent calls back into this class via WNDPROC now that we've been
  // destroyed.
  ClearUserData();
}

void HWNDMessageHandler::Init(HWND parent, const gfx::Rect& bounds) {
  TRACE_EVENT0("views", "HWNDMessageHandler::Init");
  GetMonitorAndRects(bounds.ToRECT(), &last_monitor_, &last_monitor_rect_,
                     &last_work_area_);

  // Create the window.
  WindowImpl::Init(parent, bounds);
  // TODO(ananta)
  // Remove the scrolling hack code once we have scrolling working well.
#if defined(ENABLE_SCROLL_HACK)
  // Certain trackpad drivers on Windows have bugs where in they don't generate
  // WM_MOUSEWHEEL messages for the trackpoint and trackpad scrolling gestures
  // unless there is an entry for Chrome with the class name of the Window.
  // These drivers check if the window under the trackpoint has the WS_VSCROLL/
  // WS_HSCROLL style and if yes they generate the legacy WM_VSCROLL/WM_HSCROLL
  // messages. We add these styles to ensure that trackpad/trackpoint scrolling
  // work.
  // TODO(ananta)
  // Look into moving the WS_VSCROLL and WS_HSCROLL style setting logic to the
  // CalculateWindowStylesFromInitParams function. Doing it there seems to
  // cause some interactive tests to fail. Investigation needed.
  if (IsTopLevelWindow(hwnd())) {
    long current_style = ::GetWindowLong(hwnd(), GWL_STYLE);
    if (!(current_style & WS_POPUP)) {
      AddScrollStylesToWindow(hwnd());
      needs_scroll_styles_ = true;
    }
  }
#endif

  prop_window_target_.reset(new ui::ViewProp(hwnd(),
                            ui::WindowEventTarget::kWin32InputEventTarget,
                            static_cast<ui::WindowEventTarget*>(this)));
}

void HWNDMessageHandler::InitModalType(ui::ModalType modal_type) {
  if (modal_type == ui::MODAL_TYPE_NONE)
    return;
  // We implement modality by crawling up the hierarchy of windows starting
  // at the owner, disabling all of them so that they don't receive input
  // messages.
  HWND start = ::GetWindow(hwnd(), GW_OWNER);
  while (start) {
    ::EnableWindow(start, FALSE);
    start = ::GetParent(start);
  }
}

void HWNDMessageHandler::Close() {
  if (!IsWindow(hwnd()))
    return;  // No need to do anything.

  // Let's hide ourselves right away.
  Hide();

  // Modal dialog windows disable their owner windows; re-enable them now so
  // they can activate as foreground windows upon this window's destruction.
  RestoreEnabledIfNecessary();

  if (!waiting_for_close_now_) {
    // And we delay the close so that if we are called from an ATL callback,
    // we don't destroy the window before the callback returned (as the caller
    // may delete ourselves on destroy and the ATL callback would still
    // dereference us when the callback returns).
    waiting_for_close_now_ = true;
    base::MessageLoop::current()->PostTask(
        FROM_HERE,
        base::Bind(&HWNDMessageHandler::CloseNow, weak_factory_.GetWeakPtr()));
  }
}

void HWNDMessageHandler::CloseNow() {
  // We may already have been destroyed if the selection resulted in a tab
  // switch which will have reactivated the browser window and closed us, so
  // we need to check to see if we're still a window before trying to destroy
  // ourself.
  waiting_for_close_now_ = false;
  if (IsWindow(hwnd()))
    DestroyWindow(hwnd());
}

gfx::Rect HWNDMessageHandler::GetWindowBoundsInScreen() const {
  RECT r;
  GetWindowRect(hwnd(), &r);
  return gfx::Rect(r);
}

gfx::Rect HWNDMessageHandler::GetClientAreaBoundsInScreen() const {
  RECT r;
  GetClientRect(hwnd(), &r);
  POINT point = { r.left, r.top };
  ClientToScreen(hwnd(), &point);
  return gfx::Rect(point.x, point.y, r.right - r.left, r.bottom - r.top);
}

gfx::Rect HWNDMessageHandler::GetRestoredBounds() const {
  // If we're in fullscreen mode, we've changed the normal bounds to the monitor
  // rect, so return the saved bounds instead.
  if (fullscreen_handler_->fullscreen())
    return fullscreen_handler_->GetRestoreBounds();

  gfx::Rect bounds;
  GetWindowPlacement(&bounds, NULL);
  return bounds;
}

gfx::Rect HWNDMessageHandler::GetClientAreaBounds() const {
  if (IsMinimized())
    return gfx::Rect();
  if (delegate_->WidgetSizeIsClientSize())
    return GetClientAreaBoundsInScreen();
  return GetWindowBoundsInScreen();
}

void HWNDMessageHandler::GetWindowPlacement(
    gfx::Rect* bounds,
    ui::WindowShowState* show_state) const {
  WINDOWPLACEMENT wp;
  wp.length = sizeof(wp);
  const bool succeeded = !!::GetWindowPlacement(hwnd(), &wp);
  DCHECK(succeeded);

  if (bounds != NULL) {
    if (wp.showCmd == SW_SHOWNORMAL) {
      // GetWindowPlacement can return misleading position if a normalized
      // window was resized using Aero Snap feature (see comment 9 in bug
      // 36421). As a workaround, using GetWindowRect for normalized windows.
      const bool succeeded = GetWindowRect(hwnd(), &wp.rcNormalPosition) != 0;
      DCHECK(succeeded);

      *bounds = gfx::Rect(wp.rcNormalPosition);
    } else {
      MONITORINFO mi;
      mi.cbSize = sizeof(mi);
      const bool succeeded = GetMonitorInfo(
          MonitorFromWindow(hwnd(), MONITOR_DEFAULTTONEAREST), &mi) != 0;
      DCHECK(succeeded);

      *bounds = gfx::Rect(wp.rcNormalPosition);
      // Convert normal position from workarea coordinates to screen
      // coordinates.
      bounds->Offset(mi.rcWork.left - mi.rcMonitor.left,
                     mi.rcWork.top - mi.rcMonitor.top);
    }
  }

  if (show_state) {
    if (wp.showCmd == SW_SHOWMAXIMIZED)
      *show_state = ui::SHOW_STATE_MAXIMIZED;
    else if (wp.showCmd == SW_SHOWMINIMIZED)
      *show_state = ui::SHOW_STATE_MINIMIZED;
    else
      *show_state = ui::SHOW_STATE_NORMAL;
  }
}

void HWNDMessageHandler::SetBounds(const gfx::Rect& bounds_in_pixels) {
  LONG style = GetWindowLong(hwnd(), GWL_STYLE);
  if (style & WS_MAXIMIZE)
    SetWindowLong(hwnd(), GWL_STYLE, style & ~WS_MAXIMIZE);
  SetWindowPos(hwnd(), NULL, bounds_in_pixels.x(), bounds_in_pixels.y(),
               bounds_in_pixels.width(), bounds_in_pixels.height(),
               SWP_NOACTIVATE | SWP_NOZORDER);
}

void HWNDMessageHandler::SetSize(const gfx::Size& size) {
  SetWindowPos(hwnd(), NULL, 0, 0, size.width(), size.height(),
               SWP_NOACTIVATE | SWP_NOZORDER | SWP_NOMOVE);
}

void HWNDMessageHandler::CenterWindow(const gfx::Size& size) {
  HWND parent = GetParent(hwnd());
  if (!IsWindow(hwnd()))
    parent = ::GetWindow(hwnd(), GW_OWNER);
  gfx::CenterAndSizeWindow(parent, hwnd(), size);
}

void HWNDMessageHandler::SetRegion(HRGN region) {
  custom_window_region_.Set(region);
  ResetWindowRegion(false, true);
  UpdateDwmNcRenderingPolicy();
}

void HWNDMessageHandler::StackAbove(HWND other_hwnd) {
  SetWindowPos(hwnd(), other_hwnd, 0, 0, 0, 0,
               SWP_NOSIZE | SWP_NOMOVE | SWP_NOACTIVATE);
}

void HWNDMessageHandler::StackAtTop() {
  SetWindowPos(hwnd(), HWND_TOP, 0, 0, 0, 0,
               SWP_NOSIZE | SWP_NOMOVE | SWP_NOACTIVATE);
}

void HWNDMessageHandler::Show() {
  if (IsWindow(hwnd())) {
    if (!(GetWindowLong(hwnd(), GWL_EXSTYLE) & WS_EX_TRANSPARENT) &&
        !(GetWindowLong(hwnd(), GWL_EXSTYLE) & WS_EX_NOACTIVATE)) {
      ShowWindowWithState(ui::SHOW_STATE_NORMAL);
    } else {
      ShowWindowWithState(ui::SHOW_STATE_INACTIVE);
    }
  }
}

void HWNDMessageHandler::ShowWindowWithState(ui::WindowShowState show_state) {
  TRACE_EVENT0("views", "HWNDMessageHandler::ShowWindowWithState");
  DWORD native_show_state;
  switch (show_state) {
    case ui::SHOW_STATE_INACTIVE:
      native_show_state = SW_SHOWNOACTIVATE;
      break;
    case ui::SHOW_STATE_MAXIMIZED:
      native_show_state = SW_SHOWMAXIMIZED;
      break;
    case ui::SHOW_STATE_MINIMIZED:
      native_show_state = SW_SHOWMINIMIZED;
      break;
    default:
      native_show_state = delegate_->GetInitialShowState();
      break;
  }

  ShowWindow(hwnd(), native_show_state);
  // When launched from certain programs like bash and Windows Live Messenger,
  // show_state is set to SW_HIDE, so we need to correct that condition. We
  // don't just change show_state to SW_SHOWNORMAL because MSDN says we must
  // always first call ShowWindow with the specified value from STARTUPINFO,
  // otherwise all future ShowWindow calls will be ignored (!!#@@#!). Instead,
  // we call ShowWindow again in this case.
  if (native_show_state == SW_HIDE) {
    native_show_state = SW_SHOWNORMAL;
    ShowWindow(hwnd(), native_show_state);
  }

  // We need to explicitly activate the window if we've been shown with a state
  // that should activate, because if we're opened from a desktop shortcut while
  // an existing window is already running it doesn't seem to be enough to use
  // one of these flags to activate the window.
  if (native_show_state == SW_SHOWNORMAL ||
      native_show_state == SW_SHOWMAXIMIZED)
    Activate();

  if (!delegate_->HandleInitialFocus(show_state))
    SetInitialFocus();
}

void HWNDMessageHandler::ShowMaximizedWithBounds(const gfx::Rect& bounds) {
  WINDOWPLACEMENT placement = { 0 };
  placement.length = sizeof(WINDOWPLACEMENT);
  placement.showCmd = SW_SHOWMAXIMIZED;
  placement.rcNormalPosition = bounds.ToRECT();
  SetWindowPlacement(hwnd(), &placement);
}

void HWNDMessageHandler::Hide() {
  if (IsWindow(hwnd())) {
    // NOTE: Be careful not to activate any windows here (for example, calling
    // ShowWindow(SW_HIDE) will automatically activate another window).  This
    // code can be called while a window is being deactivated, and activating
    // another window will screw up the activation that is already in progress.
    SetWindowPos(hwnd(), NULL, 0, 0, 0, 0,
                 SWP_HIDEWINDOW | SWP_NOACTIVATE | SWP_NOMOVE |
                 SWP_NOREPOSITION | SWP_NOSIZE | SWP_NOZORDER);
  }
}

void HWNDMessageHandler::Maximize() {
  ExecuteSystemMenuCommand(SC_MAXIMIZE);
}

void HWNDMessageHandler::Minimize() {
  ExecuteSystemMenuCommand(SC_MINIMIZE);
  delegate_->HandleNativeBlur(NULL);
}

void HWNDMessageHandler::Restore() {
  ExecuteSystemMenuCommand(SC_RESTORE);
}

void HWNDMessageHandler::Activate() {
  if (IsMinimized())
    ::ShowWindow(hwnd(), SW_RESTORE);
  ::SetWindowPos(hwnd(), HWND_TOP, 0, 0, 0, 0, SWP_NOSIZE | SWP_NOMOVE);
  SetForegroundWindow(hwnd());
}

void HWNDMessageHandler::Deactivate() {
  HWND next_hwnd = ::GetNextWindow(hwnd(), GW_HWNDNEXT);
  while (next_hwnd) {
    if (::IsWindowVisible(next_hwnd)) {
      ::SetForegroundWindow(next_hwnd);
      return;
    }
    next_hwnd = ::GetNextWindow(next_hwnd, GW_HWNDNEXT);
  }
}

void HWNDMessageHandler::SetAlwaysOnTop(bool on_top) {
  ::SetWindowPos(hwnd(), on_top ? HWND_TOPMOST : HWND_NOTOPMOST,
                 0, 0, 0, 0, SWP_NOMOVE | SWP_NOSIZE | SWP_NOACTIVATE);
}

bool HWNDMessageHandler::IsVisible() const {
  return !!::IsWindowVisible(hwnd());
}

bool HWNDMessageHandler::IsActive() const {
  return GetActiveWindow() == hwnd();
}

bool HWNDMessageHandler::IsMinimized() const {
  return !!::IsIconic(hwnd());
}

bool HWNDMessageHandler::IsMaximized() const {
  return !!::IsZoomed(hwnd());
}

bool HWNDMessageHandler::IsAlwaysOnTop() const {
  return (GetWindowLong(hwnd(), GWL_EXSTYLE) & WS_EX_TOPMOST) != 0;
}

bool HWNDMessageHandler::RunMoveLoop(const gfx::Vector2d& drag_offset,
                                     bool hide_on_escape) {
  ReleaseCapture();
  MoveLoopMouseWatcher watcher(this, hide_on_escape);
  // In Aura, we handle touch events asynchronously. So we need to allow nested
  // tasks while in windows move loop.
  base::MessageLoop::ScopedNestableTaskAllower allow_nested(
      base::MessageLoop::current());

  SendMessage(hwnd(), WM_SYSCOMMAND, SC_MOVE | 0x0002, GetMessagePos());
  // Windows doesn't appear to offer a way to determine whether the user
  // canceled the move or not. We assume if the user released the mouse it was
  // successful.
  return watcher.got_mouse_up();
}

void HWNDMessageHandler::EndMoveLoop() {
  SendMessage(hwnd(), WM_CANCELMODE, 0, 0);
}

void HWNDMessageHandler::SendFrameChanged() {
  SetWindowPos(hwnd(), NULL, 0, 0, 0, 0,
      SWP_FRAMECHANGED | SWP_NOACTIVATE | SWP_NOCOPYBITS |
      SWP_NOMOVE | SWP_NOOWNERZORDER | SWP_NOREPOSITION |
      SWP_NOSENDCHANGING | SWP_NOSIZE | SWP_NOZORDER);
}

void HWNDMessageHandler::FlashFrame(bool flash) {
  FLASHWINFO fwi;
  fwi.cbSize = sizeof(fwi);
  fwi.hwnd = hwnd();
  if (flash) {
    fwi.dwFlags = FLASHW_ALL;
    fwi.uCount = 4;
    fwi.dwTimeout = 0;
  } else {
    fwi.dwFlags = FLASHW_STOP;
  }
  FlashWindowEx(&fwi);
}

void HWNDMessageHandler::ClearNativeFocus() {
  ::SetFocus(hwnd());
}

void HWNDMessageHandler::SetCapture() {
  DCHECK(!HasCapture());
  ::SetCapture(hwnd());
}

void HWNDMessageHandler::ReleaseCapture() {
  if (HasCapture())
    ::ReleaseCapture();
}

bool HWNDMessageHandler::HasCapture() const {
  return ::GetCapture() == hwnd();
}

void HWNDMessageHandler::SetVisibilityChangedAnimationsEnabled(bool enabled) {
  if (base::win::GetVersion() >= base::win::VERSION_VISTA) {
    int dwm_value = enabled ? FALSE : TRUE;
    DwmSetWindowAttribute(
        hwnd(), DWMWA_TRANSITIONS_FORCEDISABLED, &dwm_value, sizeof(dwm_value));
  }
}

bool HWNDMessageHandler::SetTitle(const base::string16& title) {
  base::string16 current_title;
  size_t len_with_null = GetWindowTextLength(hwnd()) + 1;
  if (len_with_null == 1 && title.length() == 0)
    return false;
  if (len_with_null - 1 == title.length() &&
      GetWindowText(
          hwnd(), WriteInto(&current_title, len_with_null), len_with_null) &&
      current_title == title)
    return false;
  SetWindowText(hwnd(), title.c_str());
  return true;
}

void HWNDMessageHandler::SetCursor(HCURSOR cursor) {
  if (cursor) {
    previous_cursor_ = ::SetCursor(cursor);
    current_cursor_ = cursor;
  } else if (previous_cursor_) {
    ::SetCursor(previous_cursor_);
    previous_cursor_ = NULL;
  }
}

void HWNDMessageHandler::FrameTypeChanged() {
  // Called when the frame type could possibly be changing (theme change or
  // DWM composition change).
  UpdateDwmNcRenderingPolicy();

  // Don't redraw the window here, because we need to hide and show the window
  // which will also trigger a redraw.
  ResetWindowRegion(true, false);

  // The non-client view needs to update too.
  delegate_->HandleFrameChanged();

  if (IsVisible() && !delegate_->IsUsingCustomFrame()) {
    // For some reason, we need to hide the window after we change from a custom
    // frame to a native frame.  If we don't, the client area will be filled
    // with black.  This seems to be related to an interaction between DWM and
    // SetWindowRgn, but the details aren't clear. Additionally, we need to
    // specify SWP_NOZORDER here, otherwise if you have multiple chrome windows
    // open they will re-appear with a non-deterministic Z-order.
    UINT flags = SWP_NOMOVE | SWP_NOSIZE | SWP_NOZORDER;
    SetWindowPos(hwnd(), NULL, 0, 0, 0, 0, flags | SWP_HIDEWINDOW);
    SetWindowPos(hwnd(), NULL, 0, 0, 0, 0, flags | SWP_SHOWWINDOW);
    // Invalidate the window to force a paint. There may be child windows which
    // could resize in this context. Don't paint right away.
    ::InvalidateRect(hwnd(), NULL, FALSE);
  }

  // WM_DWMCOMPOSITIONCHANGED is only sent to top level windows, however we want
  // to notify our children too, since we can have MDI child windows who need to
  // update their appearance.
  EnumChildWindows(hwnd(), &SendDwmCompositionChanged, NULL);
}

void HWNDMessageHandler::SchedulePaintInRect(const gfx::Rect& rect) {
  if (use_layered_buffer_) {
    // We must update the back-buffer immediately, since Windows' handling of
    // invalid rects is somewhat mysterious.
    invalid_rect_.Union(rect);

    // In some situations, such as drag and drop, when Windows itself runs a
    // nested message loop our message loop appears to be starved and we don't
    // receive calls to DidProcessMessage(). This only seems to affect layered
    // windows, so we schedule a redraw manually using a task, since those never
    // seem to be starved. Also, wtf.
    if (!waiting_for_redraw_layered_window_contents_) {
      waiting_for_redraw_layered_window_contents_ = true;
      base::MessageLoop::current()->PostTask(
          FROM_HERE,
          base::Bind(&HWNDMessageHandler::RedrawLayeredWindowContents,
                     weak_factory_.GetWeakPtr()));
    }
  } else {
    // InvalidateRect() expects client coordinates.
    RECT r = rect.ToRECT();
    InvalidateRect(hwnd(), &r, FALSE);
  }
}

void HWNDMessageHandler::SetOpacity(BYTE opacity) {
  layered_alpha_ = opacity;
}

void HWNDMessageHandler::SetWindowIcons(const gfx::ImageSkia& window_icon,
                                        const gfx::ImageSkia& app_icon) {
  if (!window_icon.isNull()) {
    HICON windows_icon = IconUtil::CreateHICONFromSkBitmap(
        *window_icon.bitmap());
    // We need to make sure to destroy the previous icon, otherwise we'll leak
    // these GDI objects until we crash!
    HICON old_icon = reinterpret_cast<HICON>(
        SendMessage(hwnd(), WM_SETICON, ICON_SMALL,
                    reinterpret_cast<LPARAM>(windows_icon)));
    if (old_icon)
      DestroyIcon(old_icon);
  }
  if (!app_icon.isNull()) {
    HICON windows_icon = IconUtil::CreateHICONFromSkBitmap(*app_icon.bitmap());
    HICON old_icon = reinterpret_cast<HICON>(
        SendMessage(hwnd(), WM_SETICON, ICON_BIG,
                    reinterpret_cast<LPARAM>(windows_icon)));
    if (old_icon)
      DestroyIcon(old_icon);
  }
}

////////////////////////////////////////////////////////////////////////////////
// HWNDMessageHandler, InputMethodDelegate implementation:

void HWNDMessageHandler::DispatchKeyEventPostIME(const ui::KeyEvent& key) {
  SetMsgHandled(delegate_->HandleKeyEvent(key));
}

////////////////////////////////////////////////////////////////////////////////
// HWNDMessageHandler, gfx::WindowImpl overrides:

HICON HWNDMessageHandler::GetDefaultWindowIcon() const {
  if (use_system_default_icon_)
    return NULL;
  return ViewsDelegate::views_delegate ?
      ViewsDelegate::views_delegate->GetDefaultWindowIcon() : NULL;
}

LRESULT HWNDMessageHandler::OnWndProc(UINT message,
                                      WPARAM w_param,
                                      LPARAM l_param) {
  HWND window = hwnd();
  LRESULT result = 0;

  if (delegate_ && delegate_->PreHandleMSG(message, w_param, l_param, &result))
    return result;

  // Otherwise we handle everything else.
  // NOTE: We inline ProcessWindowMessage() as 'this' may be destroyed during
  // dispatch and ProcessWindowMessage() doesn't deal with that well.
  const BOOL old_msg_handled = msg_handled_;
  base::WeakPtr<HWNDMessageHandler> ref(weak_factory_.GetWeakPtr());
  const BOOL processed =
      _ProcessWindowMessage(window, message, w_param, l_param, result, 0);
  if (!ref)
    return 0;
  msg_handled_ = old_msg_handled;

  if (!processed)
    result = DefWindowProc(window, message, w_param, l_param);

  // DefWindowProc() may have destroyed the window in a nested message loop.
  if (!::IsWindow(window))
    return result;

  if (delegate_)
    delegate_->PostHandleMSG(message, w_param, l_param);
  if (message == WM_NCDESTROY) {
    if (delegate_)
      delegate_->HandleDestroyed();
  }

  // Only top level widget should store/restore focus.
  if (message == WM_ACTIVATE && delegate_->CanSaveFocus())
    PostProcessActivateMessage(LOWORD(w_param), !!HIWORD(w_param));

  if (message == WM_ENABLE && restore_focus_when_enabled_) {
    // This path should be executed only for top level as
    // restore_focus_when_enabled_ is set in PostProcessActivateMessage.
    DCHECK(delegate_->CanSaveFocus());
    restore_focus_when_enabled_ = false;
    delegate_->RestoreFocusOnEnable();
  }
  return result;
}

LRESULT HWNDMessageHandler::HandleMouseMessage(unsigned int message,
                                               WPARAM w_param,
                                               LPARAM l_param) {
  // Don't track forwarded mouse messages. We expect the caller to track the
  // mouse.
  return HandleMouseEventInternal(message, w_param, l_param, false);
}

LRESULT HWNDMessageHandler::HandleTouchMessage(unsigned int message,
                                               WPARAM w_param,
                                               LPARAM l_param) {
  return OnTouchEvent(message, w_param, l_param);
}

LRESULT HWNDMessageHandler::HandleKeyboardMessage(unsigned int message,
                                                  WPARAM w_param,
                                                  LPARAM l_param) {
  return OnKeyEvent(message, w_param, l_param);
}

LRESULT HWNDMessageHandler::HandleScrollMessage(unsigned int message,
                                                WPARAM w_param,
                                                LPARAM l_param) {
  return OnScrollMessage(message, w_param, l_param);
}

LRESULT HWNDMessageHandler::HandleNcHitTestMessage(unsigned int message,
                                                   WPARAM w_param,
                                                   LPARAM l_param) {
  return OnNCHitTest(
      gfx::Point(CR_GET_X_LPARAM(l_param), CR_GET_Y_LPARAM(l_param)));
}

////////////////////////////////////////////////////////////////////////////////
// HWNDMessageHandler, private:

int HWNDMessageHandler::GetAppbarAutohideEdges(HMONITOR monitor) {
  autohide_factory_.InvalidateWeakPtrs();
  return Appbar::instance()->GetAutohideEdges(
      monitor,
      base::Bind(&HWNDMessageHandler::OnAppbarAutohideEdgesChanged,
                 autohide_factory_.GetWeakPtr()));
}

void HWNDMessageHandler::OnAppbarAutohideEdgesChanged() {
  // This triggers querying WM_NCCALCSIZE again.
  RECT client;
  GetWindowRect(hwnd(), &client);
  SetWindowPos(hwnd(), NULL, client.left, client.top,
               client.right - client.left, client.bottom - client.top,
               SWP_FRAMECHANGED);
}

void HWNDMessageHandler::SetInitialFocus() {
  if (!(GetWindowLong(hwnd(), GWL_EXSTYLE) & WS_EX_TRANSPARENT) &&
      !(GetWindowLong(hwnd(), GWL_EXSTYLE) & WS_EX_NOACTIVATE)) {
    // The window does not get keyboard messages unless we focus it.
    SetFocus(hwnd());
  }
}

void HWNDMessageHandler::PostProcessActivateMessage(int activation_state,
                                                    bool minimized) {
  DCHECK(delegate_->CanSaveFocus());

  bool active = activation_state != WA_INACTIVE && !minimized;
  if (delegate_->CanActivate())
    delegate_->HandleActivationChanged(active);

  if (!active) {
    // We might get activated/inactivated without being enabled, so we need to
    // clear restore_focus_when_enabled_.
    restore_focus_when_enabled_ = false;
    delegate_->SaveFocusOnDeactivate();
  } else {
    // We must restore the focus after the message has been DefProc'ed as it
    // does set the focus to the last focused HWND.
    // Note that if the window is not enabled, we cannot restore the focus as
    // calling ::SetFocus on a child of the non-enabled top-window would fail.
    // This is the case when showing a modal dialog (such as 'open file',
    // 'print'...) from a different thread.
    // In that case we delay the focus restoration to when the window is enabled
    // again.
    if (!IsWindowEnabled(hwnd())) {
      DCHECK(!restore_focus_when_enabled_);
      restore_focus_when_enabled_ = true;
      return;
    }
    delegate_->RestoreFocusOnActivate();
  }
}

void HWNDMessageHandler::RestoreEnabledIfNecessary() {
  if (delegate_->IsModal() && !restored_enabled_) {
    restored_enabled_ = true;
    // If we were run modally, we need to undo the disabled-ness we inflicted on
    // the owner's parent hierarchy.
    HWND start = ::GetWindow(hwnd(), GW_OWNER);
    while (start) {
      ::EnableWindow(start, TRUE);
      start = ::GetParent(start);
    }
  }
}

void HWNDMessageHandler::ExecuteSystemMenuCommand(int command) {
  if (command)
    SendMessage(hwnd(), WM_SYSCOMMAND, command, 0);
}

void HWNDMessageHandler::TrackMouseEvents(DWORD mouse_tracking_flags) {
  // Begin tracking mouse events for this HWND so that we get WM_MOUSELEAVE
  // when the user moves the mouse outside this HWND's bounds.
  if (active_mouse_tracking_flags_ == 0 || mouse_tracking_flags & TME_CANCEL) {
    if (mouse_tracking_flags & TME_CANCEL) {
      // We're about to cancel active mouse tracking, so empty out the stored
      // state.
      active_mouse_tracking_flags_ = 0;
    } else {
      active_mouse_tracking_flags_ = mouse_tracking_flags;
    }

    TRACKMOUSEEVENT tme;
    tme.cbSize = sizeof(tme);
    tme.dwFlags = mouse_tracking_flags;
    tme.hwndTrack = hwnd();
    tme.dwHoverTime = 0;
    TrackMouseEvent(&tme);
  } else if (mouse_tracking_flags != active_mouse_tracking_flags_) {
    TrackMouseEvents(active_mouse_tracking_flags_ | TME_CANCEL);
    TrackMouseEvents(mouse_tracking_flags);
  }
}

void HWNDMessageHandler::ClientAreaSizeChanged() {
  gfx::Size s = GetClientAreaBounds().size();
  delegate_->HandleClientSizeChanged(s);
  if (use_layered_buffer_)
    layered_window_contents_.reset(new gfx::Canvas(s, 1.0f, false));
}

bool HWNDMessageHandler::GetClientAreaInsets(gfx::Insets* insets) const {
  if (delegate_->GetClientAreaInsets(insets))
    return true;
  DCHECK(insets->empty());

  // Returning false causes the default handling in OnNCCalcSize() to
  // be invoked.
  if (!delegate_->IsWidgetWindow() ||
      (!delegate_->IsUsingCustomFrame() && !remove_standard_frame_)) {
    return false;
  }

  if (IsMaximized()) {
    // Windows automatically adds a standard width border to all sides when a
    // window is maximized.
    int border_thickness = GetSystemMetrics(SM_CXSIZEFRAME);
    if (remove_standard_frame_)
      border_thickness -= 1;
    *insets = gfx::Insets(
        border_thickness, border_thickness, border_thickness, border_thickness);
    return true;
  }

  *insets = gfx::Insets();
  return true;
}

void HWNDMessageHandler::ResetWindowRegion(bool force, bool redraw) {
  // A native frame uses the native window region, and we don't want to mess
  // with it.
  // WS_EX_COMPOSITED is used instead of WS_EX_LAYERED under aura. WS_EX_LAYERED
  // automatically makes clicks on transparent pixels fall through, that isn't
  // the case with WS_EX_COMPOSITED. So, we route WS_EX_COMPOSITED through to
  // the delegate to allow for a custom hit mask.
  if ((window_ex_style() & WS_EX_COMPOSITED) == 0 && !custom_window_region_ &&
      (!delegate_->IsUsingCustomFrame() || !delegate_->IsWidgetWindow())) {
    if (force)
      SetWindowRgn(hwnd(), NULL, redraw);
    return;
  }

  // Changing the window region is going to force a paint. Only change the
  // window region if the region really differs.
  HRGN current_rgn = CreateRectRgn(0, 0, 0, 0);
  int current_rgn_result = GetWindowRgn(hwnd(), current_rgn);

  RECT window_rect;
  GetWindowRect(hwnd(), &window_rect);
  HRGN new_region;
  if (custom_window_region_) {
    new_region = ::CreateRectRgn(0, 0, 0, 0);
    ::CombineRgn(new_region, custom_window_region_.Get(), NULL, RGN_COPY);
  } else if (IsMaximized()) {
    HMONITOR monitor = MonitorFromWindow(hwnd(), MONITOR_DEFAULTTONEAREST);
    MONITORINFO mi;
    mi.cbSize = sizeof mi;
    GetMonitorInfo(monitor, &mi);
    RECT work_rect = mi.rcWork;
    OffsetRect(&work_rect, -window_rect.left, -window_rect.top);
    new_region = CreateRectRgnIndirect(&work_rect);
  } else {
    gfx::Path window_mask;
    delegate_->GetWindowMask(gfx::Size(window_rect.right - window_rect.left,
                                       window_rect.bottom - window_rect.top),
                             &window_mask);
    new_region = gfx::CreateHRGNFromSkPath(window_mask);
  }

  if (current_rgn_result == ERROR || !EqualRgn(current_rgn, new_region)) {
    // SetWindowRgn takes ownership of the HRGN created by CreateNativeRegion.
    SetWindowRgn(hwnd(), new_region, redraw);
  } else {
    DeleteObject(new_region);
  }

  DeleteObject(current_rgn);
}

void HWNDMessageHandler::UpdateDwmNcRenderingPolicy() {
  if (base::win::GetVersion() < base::win::VERSION_VISTA)
    return;

  DWMNCRENDERINGPOLICY policy =
      custom_window_region_ || delegate_->IsUsingCustomFrame() ?
          DWMNCRP_DISABLED : DWMNCRP_ENABLED;

  DwmSetWindowAttribute(hwnd(), DWMWA_NCRENDERING_POLICY,
                        &policy, sizeof(DWMNCRENDERINGPOLICY));
}

LRESULT HWNDMessageHandler::DefWindowProcWithRedrawLock(UINT message,
                                                        WPARAM w_param,
                                                        LPARAM l_param) {
  ScopedRedrawLock lock(this);
  // The Widget and HWND can be destroyed in the call to DefWindowProc, so use
  // the WeakPtrFactory to avoid unlocking (and crashing) after destruction.
  base::WeakPtr<HWNDMessageHandler> ref(weak_factory_.GetWeakPtr());
  LRESULT result = DefWindowProc(hwnd(), message, w_param, l_param);
  if (!ref)
    lock.CancelUnlockOperation();
  return result;
}

void HWNDMessageHandler::LockUpdates(bool force) {
  // We skip locked updates when Aero is on for two reasons:
  // 1. Because it isn't necessary
  // 2. Because toggling the WS_VISIBLE flag may occur while the GPU process is
  //    attempting to present a child window's backbuffer onscreen. When these
  //    two actions race with one another, the child window will either flicker
  //    or will simply stop updating entirely.
  if ((force || !ui::win::IsAeroGlassEnabled()) && ++lock_updates_count_ == 1) {
    SetWindowLong(hwnd(), GWL_STYLE,
                  GetWindowLong(hwnd(), GWL_STYLE) & ~WS_VISIBLE);
  }
}

void HWNDMessageHandler::UnlockUpdates(bool force) {
  if ((force || !ui::win::IsAeroGlassEnabled()) && --lock_updates_count_ <= 0) {
    SetWindowLong(hwnd(), GWL_STYLE,
                  GetWindowLong(hwnd(), GWL_STYLE) | WS_VISIBLE);
    lock_updates_count_ = 0;
  }
}

void HWNDMessageHandler::RedrawLayeredWindowContents() {
  waiting_for_redraw_layered_window_contents_ = false;
  if (invalid_rect_.IsEmpty())
    return;

  // We need to clip to the dirty rect ourselves.
  layered_window_contents_->sk_canvas()->save();
  double scale = gfx::win::GetDeviceScaleFactor();
  layered_window_contents_->sk_canvas()->scale(
      SkScalar(scale),SkScalar(scale));
  layered_window_contents_->ClipRect(invalid_rect_);
  delegate_->PaintLayeredWindow(layered_window_contents_.get());
  layered_window_contents_->sk_canvas()->scale(
      SkScalar(1.0/scale),SkScalar(1.0/scale));
  layered_window_contents_->sk_canvas()->restore();

  RECT wr;
  GetWindowRect(hwnd(), &wr);
  SIZE size = {wr.right - wr.left, wr.bottom - wr.top};
  POINT position = {wr.left, wr.top};
  HDC dib_dc = skia::BeginPlatformPaint(layered_window_contents_->sk_canvas());
  POINT zero = {0, 0};
  BLENDFUNCTION blend = {AC_SRC_OVER, 0, layered_alpha_, AC_SRC_ALPHA};
  UpdateLayeredWindow(hwnd(), NULL, &position, &size, dib_dc, &zero,
                      RGB(0xFF, 0xFF, 0xFF), &blend, ULW_ALPHA);
  invalid_rect_.SetRect(0, 0, 0, 0);
  skia::EndPlatformPaint(layered_window_contents_->sk_canvas());
}

void HWNDMessageHandler::ForceRedrawWindow(int attempts) {
  if (ui::IsWorkstationLocked()) {
    // Presents will continue to fail as long as the input desktop is
    // unavailable.
    if (--attempts <= 0)
      return;
    base::MessageLoop::current()->PostDelayedTask(
        FROM_HERE,
        base::Bind(&HWNDMessageHandler::ForceRedrawWindow,
                   weak_factory_.GetWeakPtr(),
                   attempts),
        base::TimeDelta::FromMilliseconds(500));
    return;
  }
  InvalidateRect(hwnd(), NULL, FALSE);
}

// Message handlers ------------------------------------------------------------

void HWNDMessageHandler::OnActivateApp(BOOL active, DWORD thread_id) {
  if (delegate_->IsWidgetWindow() && !active &&
      thread_id != GetCurrentThreadId()) {
    delegate_->HandleAppDeactivated();
    // Also update the native frame if it is rendering the non-client area.
    if (!remove_standard_frame_ && !delegate_->IsUsingCustomFrame())
      DefWindowProcWithRedrawLock(WM_NCACTIVATE, FALSE, 0);
  }
}

BOOL HWNDMessageHandler::OnAppCommand(HWND window,
                                      short command,
                                      WORD device,
                                      int keystate) {
  BOOL handled = !!delegate_->HandleAppCommand(command);
  SetMsgHandled(handled);
  // Make sure to return TRUE if the event was handled or in some cases the
  // system will execute the default handler which can cause bugs like going
  // forward or back two pages instead of one.
  return handled;
}

void HWNDMessageHandler::OnCancelMode() {
  delegate_->HandleCancelMode();
  // Need default handling, otherwise capture and other things aren't canceled.
  SetMsgHandled(FALSE);
}

void HWNDMessageHandler::OnCaptureChanged(HWND window) {
  delegate_->HandleCaptureLost();
}

void HWNDMessageHandler::OnClose() {
  delegate_->HandleClose();
}

void HWNDMessageHandler::OnCommand(UINT notification_code,
                                   int command,
                                   HWND window) {
  // If the notification code is > 1 it means it is control specific and we
  // should ignore it.
  if (notification_code > 1 || delegate_->HandleAppCommand(command))
    SetMsgHandled(FALSE);
}

LRESULT HWNDMessageHandler::OnCreate(CREATESTRUCT* create_struct) {
  use_layered_buffer_ = !!(window_ex_style() & WS_EX_LAYERED);

  if (window_ex_style() &  WS_EX_COMPOSITED) {
    if (base::win::GetVersion() >= base::win::VERSION_VISTA) {
      // This is part of the magic to emulate layered windows with Aura
      // see the explanation elsewere when we set WS_EX_COMPOSITED style.
      MARGINS margins = {-1,-1,-1,-1};
      DwmExtendFrameIntoClientArea(hwnd(), &margins);
    }
  }

  fullscreen_handler_->set_hwnd(hwnd());

  // This message initializes the window so that focus border are shown for
  // windows.
  SendMessage(hwnd(),
              WM_CHANGEUISTATE,
              MAKELPARAM(UIS_CLEAR, UISF_HIDEFOCUS),
              0);

  if (remove_standard_frame_) {
    SetWindowLong(hwnd(), GWL_STYLE,
                  GetWindowLong(hwnd(), GWL_STYLE) & ~WS_CAPTION);
    SendFrameChanged();
  }

  // Get access to a modifiable copy of the system menu.
  GetSystemMenu(hwnd(), false);

  if (base::win::GetVersion() >= base::win::VERSION_WIN7 &&
      ui::AreTouchEventsEnabled())
    RegisterTouchWindow(hwnd(), TWF_WANTPALM);

  // We need to allow the delegate to size its contents since the window may not
  // receive a size notification when its initial bounds are specified at window
  // creation time.
  ClientAreaSizeChanged();

  delegate_->HandleCreate();

  WTSRegisterSessionNotification(hwnd(), NOTIFY_FOR_THIS_SESSION);

  // TODO(beng): move more of NWW::OnCreate here.
  return 0;
}

void HWNDMessageHandler::OnDestroy() {
  WTSUnRegisterSessionNotification(hwnd());
  delegate_->HandleDestroying();
}

void HWNDMessageHandler::OnDisplayChange(UINT bits_per_pixel,
                                         const gfx::Size& screen_size) {
  delegate_->HandleDisplayChange();
}

LRESULT HWNDMessageHandler::OnDwmCompositionChanged(UINT msg,
                                                    WPARAM w_param,
                                                    LPARAM l_param) {
  if (!delegate_->IsWidgetWindow()) {
    SetMsgHandled(FALSE);
    return 0;
  }

  FrameTypeChanged();
  return 0;
}

void HWNDMessageHandler::OnEnterMenuLoop(BOOL from_track_popup_menu) {
  if (menu_depth_++ == 0)
    delegate_->HandleMenuLoop(true);
}

void HWNDMessageHandler::OnEnterSizeMove() {
  // Please refer to the comments in the OnSize function about the scrollbar
  // hack.
  // Hide the Windows scrollbar if the scroll styles are present to ensure
  // that a paint flicker does not occur while sizing.
  if (in_size_loop_ && needs_scroll_styles_)
    ShowScrollBar(hwnd(), SB_BOTH, FALSE);

  delegate_->HandleBeginWMSizeMove();
  SetMsgHandled(FALSE);
}

LRESULT HWNDMessageHandler::OnEraseBkgnd(HDC dc) {
  // Needed to prevent resize flicker.
  return 1;
}

void HWNDMessageHandler::OnExitMenuLoop(BOOL is_shortcut_menu) {
  if (--menu_depth_ == 0)
    delegate_->HandleMenuLoop(false);
  DCHECK_GE(0, menu_depth_);
}

void HWNDMessageHandler::OnExitSizeMove() {
  delegate_->HandleEndWMSizeMove();
  SetMsgHandled(FALSE);
  // Please refer to the notes in the OnSize function for information about
  // the scrolling hack.
  // We hide the Windows scrollbar in the OnEnterSizeMove function. We need
  // to add the scroll styles back to ensure that scrolling works in legacy
  // trackpoint drivers.
  if (in_size_loop_ && needs_scroll_styles_)
    AddScrollStylesToWindow(hwnd());
}

void HWNDMessageHandler::OnGetMinMaxInfo(MINMAXINFO* minmax_info) {
  gfx::Size min_window_size;
  gfx::Size max_window_size;
  delegate_->GetMinMaxSize(&min_window_size, &max_window_size);

  // Add the native frame border size to the minimum and maximum size if the
  // view reports its size as the client size.
  if (delegate_->WidgetSizeIsClientSize()) {
    RECT client_rect, window_rect;
    GetClientRect(hwnd(), &client_rect);
    GetWindowRect(hwnd(), &window_rect);
    CR_DEFLATE_RECT(&window_rect, &client_rect);
    min_window_size.Enlarge(window_rect.right - window_rect.left,
                            window_rect.bottom - window_rect.top);
    if (!max_window_size.IsEmpty()) {
      max_window_size.Enlarge(window_rect.right - window_rect.left,
                              window_rect.bottom - window_rect.top);
    }
  }
  minmax_info->ptMinTrackSize.x = min_window_size.width();
  minmax_info->ptMinTrackSize.y = min_window_size.height();
  if (max_window_size.width() || max_window_size.height()) {
    if (!max_window_size.width())
      max_window_size.set_width(GetSystemMetrics(SM_CXMAXTRACK));
    if (!max_window_size.height())
      max_window_size.set_height(GetSystemMetrics(SM_CYMAXTRACK));
    minmax_info->ptMaxTrackSize.x = max_window_size.width();
    minmax_info->ptMaxTrackSize.y = max_window_size.height();
  }
  SetMsgHandled(FALSE);
}

LRESULT HWNDMessageHandler::OnGetObject(UINT message,
                                        WPARAM w_param,
                                        LPARAM l_param) {
  LRESULT reference_result = static_cast<LRESULT>(0L);

  // Accessibility readers will send an OBJID_CLIENT message
  if (OBJID_CLIENT == l_param) {
    // Retrieve MSAA dispatch object for the root view.
    base::win::ScopedComPtr<IAccessible> root(
        delegate_->GetNativeViewAccessible());

    // Create a reference that MSAA will marshall to the client.
    reference_result = LresultFromObject(IID_IAccessible, w_param,
        static_cast<IAccessible*>(root.Detach()));
  }

  return reference_result;
}

LRESULT HWNDMessageHandler::OnImeMessages(UINT message,
                                          WPARAM w_param,
                                          LPARAM l_param) {
  LRESULT result = 0;
  SetMsgHandled(delegate_->HandleIMEMessage(
      message, w_param, l_param, &result));
  return result;
}

void HWNDMessageHandler::OnInitMenu(HMENU menu) {
  bool is_fullscreen = fullscreen_handler_->fullscreen();
  bool is_minimized = IsMinimized();
  bool is_maximized = IsMaximized();
  bool is_restored = !is_fullscreen && !is_minimized && !is_maximized;

  ScopedRedrawLock lock(this);
  EnableMenuItemByCommand(menu, SC_RESTORE, delegate_->CanResize() &&
                          (is_minimized || is_maximized));
  EnableMenuItemByCommand(menu, SC_MOVE, is_restored);
  EnableMenuItemByCommand(menu, SC_SIZE, delegate_->CanResize() && is_restored);
  EnableMenuItemByCommand(menu, SC_MAXIMIZE, delegate_->CanMaximize() &&
                          !is_fullscreen && !is_maximized);
  // TODO: unfortunately, WidgetDelegate does not declare CanMinimize() and some
  // code depends on this check, see http://crbug.com/341010.
  EnableMenuItemByCommand(menu, SC_MINIMIZE, delegate_->CanMaximize() &&
                          !is_minimized);

  if (is_maximized && delegate_->CanResize())
    ::SetMenuDefaultItem(menu, SC_RESTORE, FALSE);
  else if (!is_maximized && delegate_->CanMaximize())
    ::SetMenuDefaultItem(menu, SC_MAXIMIZE, FALSE);
}

void HWNDMessageHandler::OnInputLangChange(DWORD character_set,
                                           HKL input_language_id) {
  delegate_->HandleInputLanguageChange(character_set, input_language_id);
}

LRESULT HWNDMessageHandler::OnKeyEvent(UINT message,
                                       WPARAM w_param,
                                       LPARAM l_param) {
  MSG msg = { hwnd(), message, w_param, l_param, GetMessageTime() };
  ui::KeyEvent key(msg, message == WM_CHAR);
  if (!delegate_->HandleUntranslatedKeyEvent(key))
    DispatchKeyEventPostIME(key);
  return 0;
}

void HWNDMessageHandler::OnKillFocus(HWND focused_window) {
  delegate_->HandleNativeBlur(focused_window);
  SetMsgHandled(FALSE);
}

LRESULT HWNDMessageHandler::OnMouseActivate(UINT message,
                                            WPARAM w_param,
                                            LPARAM l_param) {
  // Please refer to the comments in the header for the touch_down_context_
  // member for the if statement below.
  if (touch_down_context_)
    return MA_NOACTIVATE;

  // On Windows, if we select the menu item by touch and if the window at the
  // location is another window on the same thread, that window gets a
  // WM_MOUSEACTIVATE message and ends up activating itself, which is not
  // correct. We workaround this by setting a property on the window at the
  // current cursor location. We check for this property in our
  // WM_MOUSEACTIVATE handler and don't activate the window if the property is
  // set.
  if (::GetProp(hwnd(), ui::kIgnoreTouchMouseActivateForWindow)) {
    ::RemoveProp(hwnd(), ui::kIgnoreTouchMouseActivateForWindow);
    return MA_NOACTIVATE;
  }
  // A child window activation should be treated as if we lost activation.
  POINT cursor_pos = {0};
  ::GetCursorPos(&cursor_pos);
  ::ScreenToClient(hwnd(), &cursor_pos);
  HWND child = ::RealChildWindowFromPoint(hwnd(), cursor_pos);
  if (::IsWindow(child) && child != hwnd() && ::IsWindowVisible(child))
    PostProcessActivateMessage(WA_INACTIVE, false);

  // TODO(beng): resolve this with the GetWindowLong() check on the subsequent
  //             line.
  if (delegate_->IsWidgetWindow())
    return delegate_->CanActivate() ? MA_ACTIVATE : MA_NOACTIVATEANDEAT;
  if (GetWindowLong(hwnd(), GWL_EXSTYLE) & WS_EX_NOACTIVATE)
    return MA_NOACTIVATE;
  SetMsgHandled(FALSE);
  return MA_ACTIVATE;
}

LRESULT HWNDMessageHandler::OnMouseRange(UINT message,
                                         WPARAM w_param,
                                         LPARAM l_param) {
  return HandleMouseEventInternal(message, w_param, l_param, true);
}

void HWNDMessageHandler::OnMove(const gfx::Point& point) {
  delegate_->HandleMove();
  SetMsgHandled(FALSE);
}

void HWNDMessageHandler::OnMoving(UINT param, const RECT* new_bounds) {
  delegate_->HandleMove();
}

LRESULT HWNDMessageHandler::OnNCActivate(UINT message,
                                         WPARAM w_param,
                                         LPARAM l_param) {
  // Per MSDN, w_param is either TRUE or FALSE. However, MSDN also hints that:
  // "If the window is minimized when this message is received, the application
  // should pass the message to the DefWindowProc function."
  // It is found out that the high word of w_param might be set when the window
  // is minimized or restored. To handle this, w_param's high word should be
  // cleared before it is converted to BOOL.
  BOOL active = static_cast<BOOL>(LOWORD(w_param));

  bool inactive_rendering_disabled = delegate_->IsInactiveRenderingDisabled();

  if (!delegate_->IsWidgetWindow()) {
    SetMsgHandled(FALSE);
    return 0;
  }

  if (!delegate_->CanActivate())
    return TRUE;

  // On activation, lift any prior restriction against rendering as inactive.
  if (active && inactive_rendering_disabled)
    delegate_->EnableInactiveRendering();

  if (delegate_->IsUsingCustomFrame()) {
    // TODO(beng, et al): Hack to redraw this window and child windows
    //     synchronously upon activation. Not all child windows are redrawing
    //     themselves leading to issues like http://crbug.com/74604
    //     We redraw out-of-process HWNDs asynchronously to avoid hanging the
    //     whole app if a child HWND belonging to a hung plugin is encountered.
    RedrawWindow(hwnd(), NULL, NULL,
                 RDW_NOCHILDREN | RDW_INVALIDATE | RDW_UPDATENOW);
    EnumChildWindows(hwnd(), EnumChildWindowsForRedraw, NULL);
  }

  // The frame may need to redraw as a result of the activation change.
  // We can get WM_NCACTIVATE before we're actually visible. If we're not
  // visible, no need to paint.
  if (IsVisible())
    delegate_->SchedulePaint();

  // Avoid DefWindowProc non-client rendering over our custom frame on newer
  // Windows versions only (breaks taskbar activation indication on XP/Vista).
  if (delegate_->IsUsingCustomFrame() &&
      base::win::GetVersion() > base::win::VERSION_VISTA) {
    SetMsgHandled(TRUE);
    return TRUE;
  }

  return DefWindowProcWithRedrawLock(
      WM_NCACTIVATE, inactive_rendering_disabled || active, 0);
}

LRESULT HWNDMessageHandler::OnNCCalcSize(BOOL mode, LPARAM l_param) {
  // We only override the default handling if we need to specify a custom
  // non-client edge width. Note that in most cases "no insets" means no
  // custom width, but in fullscreen mode or when the NonClientFrameView
  // requests it, we want a custom width of 0.

  // Let User32 handle the first nccalcsize for captioned windows
  // so it updates its internal structures (specifically caption-present)
  // Without this Tile & Cascade windows won't work.
  // See http://code.google.com/p/chromium/issues/detail?id=900
  if (is_first_nccalc_) {
    is_first_nccalc_ = false;
    if (GetWindowLong(hwnd(), GWL_STYLE) & WS_CAPTION) {
      SetMsgHandled(FALSE);
      return 0;
    }
  }

  gfx::Insets insets;
  bool got_insets = GetClientAreaInsets(&insets);
  if (!got_insets && !fullscreen_handler_->fullscreen() &&
      !(mode && remove_standard_frame_)) {
    SetMsgHandled(FALSE);
    return 0;
  }

  RECT* client_rect = mode ?
      &(reinterpret_cast<NCCALCSIZE_PARAMS*>(l_param)->rgrc[0]) :
      reinterpret_cast<RECT*>(l_param);
  client_rect->left += insets.left();
  client_rect->top += insets.top();
  client_rect->bottom -= insets.bottom();
  client_rect->right -= insets.right();
  if (IsMaximized()) {
    // Find all auto-hide taskbars along the screen edges and adjust in by the
    // thickness of the auto-hide taskbar on each such edge, so the window isn't
    // treated as a "fullscreen app", which would cause the taskbars to
    // disappear.
    HMONITOR monitor = MonitorFromWindow(hwnd(), MONITOR_DEFAULTTONULL);
    if (!monitor) {
      // We might end up here if the window was previously minimized and the
      // user clicks on the taskbar button to restore it in the previously
      // maximized position. In that case WM_NCCALCSIZE is sent before the
      // window coordinates are restored to their previous values, so our
      // (left,top) would probably be (-32000,-32000) like all minimized
      // windows. So the above MonitorFromWindow call fails, but if we check
      // the window rect given with WM_NCCALCSIZE (which is our previous
      // restored window position) we will get the correct monitor handle.
      monitor = MonitorFromRect(client_rect, MONITOR_DEFAULTTONULL);
      if (!monitor) {
        // This is probably an extreme case that we won't hit, but if we don't
        // intersect any monitor, let us not adjust the client rect since our
        // window will not be visible anyway.
        return 0;
      }
    }
    const int autohide_edges = GetAppbarAutohideEdges(monitor);
    if (autohide_edges & Appbar::EDGE_LEFT)
      client_rect->left += kAutoHideTaskbarThicknessPx;
    if (autohide_edges & Appbar::EDGE_TOP) {
      if (!delegate_->IsUsingCustomFrame()) {
        // Tricky bit.  Due to a bug in DwmDefWindowProc()'s handling of
        // WM_NCHITTEST, having any nonclient area atop the window causes the
        // caption buttons to draw onscreen but not respond to mouse
        // hover/clicks.
        // So for a taskbar at the screen top, we can't push the
        // client_rect->top down; instead, we move the bottom up by one pixel,
        // which is the smallest change we can make and still get a client area
        // less than the screen size. This is visibly ugly, but there seems to
        // be no better solution.
        --client_rect->bottom;
      } else {
        client_rect->top += kAutoHideTaskbarThicknessPx;
      }
    }
    if (autohide_edges & Appbar::EDGE_RIGHT)
      client_rect->right -= kAutoHideTaskbarThicknessPx;
    if (autohide_edges & Appbar::EDGE_BOTTOM)
      client_rect->bottom -= kAutoHideTaskbarThicknessPx;

    // We cannot return WVR_REDRAW when there is nonclient area, or Windows
    // exhibits bugs where client pixels and child HWNDs are mispositioned by
    // the width/height of the upper-left nonclient area.
    return 0;
  }

  // If the window bounds change, we're going to relayout and repaint anyway.
  // Returning WVR_REDRAW avoids an extra paint before that of the old client
  // pixels in the (now wrong) location, and thus makes actions like resizing a
  // window from the left edge look slightly less broken.
  // We special case when left or top insets are 0, since these conditions
  // actually require another repaint to correct the layout after glass gets
  // turned on and off.
  if (insets.left() == 0 || insets.top() == 0)
    return 0;
  return mode ? WVR_REDRAW : 0;
}

LRESULT HWNDMessageHandler::OnNCHitTest(const gfx::Point& point) {
  if (!delegate_->IsWidgetWindow()) {
    SetMsgHandled(FALSE);
    return 0;
  }

  // If the DWM is rendering the window controls, we need to give the DWM's
  // default window procedure first chance to handle hit testing.
  if (!remove_standard_frame_ && !delegate_->IsUsingCustomFrame()) {
    LRESULT result;
    if (DwmDefWindowProc(hwnd(), WM_NCHITTEST, 0,
                         MAKELPARAM(point.x(), point.y()), &result)) {
      return result;
    }
  }

  // First, give the NonClientView a chance to test the point to see if it
  // provides any of the non-client area.
  POINT temp = { point.x(), point.y() };
  MapWindowPoints(HWND_DESKTOP, hwnd(), &temp, 1);
  int component = delegate_->GetNonClientComponent(gfx::Point(temp));
  if (component != HTNOWHERE)
    return component;

  // Otherwise, we let Windows do all the native frame non-client handling for
  // us.
  LRESULT hit_test_code = DefWindowProc(hwnd(), WM_NCHITTEST, 0,
                                        MAKELPARAM(point.x(), point.y()));
  if (needs_scroll_styles_) {
    switch (hit_test_code) {
      // If we faked the WS_VSCROLL and WS_HSCROLL styles for this window, then
      // Windows returns the HTVSCROLL or HTHSCROLL hit test codes if we hover
      // or click on the non client portions of the window where the OS
      // scrollbars would be drawn. These hittest codes are returned even when
      // the scrollbars are hidden, which is the case in Aura. We fake the
      // hittest code as HTCLIENT in this case to ensure that we receive client
      // mouse messages as opposed to non client mouse messages.
      case HTVSCROLL:
      case HTHSCROLL:
        hit_test_code = HTCLIENT;
        break;

      case HTBOTTOMRIGHT: {
        // Normally the HTBOTTOMRIGHT hittest code is received when we hover
        // near the bottom right of the window. However due to our fake scroll
        // styles, we get this code even when we hover around the area where
        // the vertical scrollar down arrow would be drawn.
        // We check if the hittest coordinates lie in this region and if yes
        // we return HTCLIENT.
        int border_width = ::GetSystemMetrics(SM_CXSIZEFRAME);
        int border_height = ::GetSystemMetrics(SM_CYSIZEFRAME);
        int scroll_width = ::GetSystemMetrics(SM_CXVSCROLL);
        int scroll_height = ::GetSystemMetrics(SM_CYVSCROLL);
        RECT window_rect;
        ::GetWindowRect(hwnd(), &window_rect);
        window_rect.bottom -= border_height;
        window_rect.right -= border_width;
        window_rect.left = window_rect.right - scroll_width;
        window_rect.top = window_rect.bottom - scroll_height;
        POINT pt;
        pt.x = point.x();
        pt.y = point.y();
        if (::PtInRect(&window_rect, pt))
          hit_test_code = HTCLIENT;
        break;
      }

      default:
        break;
    }
  }
  return hit_test_code;
}

void HWNDMessageHandler::OnNCPaint(HRGN rgn) {
  // We only do non-client painting if we're not using the native frame.
  // It's required to avoid some native painting artifacts from appearing when
  // the window is resized.
  if (!delegate_->IsWidgetWindow() || !delegate_->IsUsingCustomFrame()) {
    SetMsgHandled(FALSE);
    return;
  }

  // We have an NC region and need to paint it. We expand the NC region to
  // include the dirty region of the root view. This is done to minimize
  // paints.
  RECT window_rect;
  GetWindowRect(hwnd(), &window_rect);

  gfx::Size root_view_size = delegate_->GetRootViewSize();
  if (gfx::Size(window_rect.right - window_rect.left,
                window_rect.bottom - window_rect.top) != root_view_size) {
    // If the size of the window differs from the size of the root view it
    // means we're being asked to paint before we've gotten a WM_SIZE. This can
    // happen when the user is interactively resizing the window. To avoid
    // mass flickering we don't do anything here. Once we get the WM_SIZE we'll
    // reset the region of the window which triggers another WM_NCPAINT and
    // all is well.
    return;
  }

  RECT dirty_region;
  // A value of 1 indicates paint all.
  if (!rgn || rgn == reinterpret_cast<HRGN>(1)) {
    dirty_region.left = 0;
    dirty_region.top = 0;
    dirty_region.right = window_rect.right - window_rect.left;
    dirty_region.bottom = window_rect.bottom - window_rect.top;
  } else {
    RECT rgn_bounding_box;
    GetRgnBox(rgn, &rgn_bounding_box);
    if (!IntersectRect(&dirty_region, &rgn_bounding_box, &window_rect))
      return;  // Dirty region doesn't intersect window bounds, bale.

    // rgn_bounding_box is in screen coordinates. Map it to window coordinates.
    OffsetRect(&dirty_region, -window_rect.left, -window_rect.top);
  }

  // In theory GetDCEx should do what we want, but I couldn't get it to work.
  // In particular the docs mentiond DCX_CLIPCHILDREN, but as far as I can tell
  // it doesn't work at all. So, instead we get the DC for the window then
  // manually clip out the children.
  HDC dc = GetWindowDC(hwnd());
  ClipState clip_state;
  clip_state.x = window_rect.left;
  clip_state.y = window_rect.top;
  clip_state.parent = hwnd();
  clip_state.dc = dc;
  EnumChildWindows(hwnd(), &ClipDCToChild,
                   reinterpret_cast<LPARAM>(&clip_state));

  gfx::Rect old_paint_region = invalid_rect_;
  if (!old_paint_region.IsEmpty()) {
    // The root view has a region that needs to be painted. Include it in the
    // region we're going to paint.

    RECT old_paint_region_crect = old_paint_region.ToRECT();
    RECT tmp = dirty_region;
    UnionRect(&dirty_region, &tmp, &old_paint_region_crect);
  }

  SchedulePaintInRect(gfx::Rect(dirty_region));

  // gfx::CanvasSkiaPaint's destructor does the actual painting. As such, wrap
  // the following in a block to force paint to occur so that we can release
  // the dc.
  if (!delegate_->HandlePaintAccelerated(gfx::Rect(dirty_region))) {
    gfx::CanvasSkiaPaint canvas(dc,
                                true,
                                dirty_region.left,
                                dirty_region.top,
                                dirty_region.right - dirty_region.left,
                                dirty_region.bottom - dirty_region.top);
    delegate_->HandlePaint(&canvas);
  }

  ReleaseDC(hwnd(), dc);
  // When using a custom frame, we want to avoid calling DefWindowProc() since
  // that may render artifacts.
  SetMsgHandled(delegate_->IsUsingCustomFrame());
}

LRESULT HWNDMessageHandler::OnNCUAHDrawCaption(UINT message,
                                               WPARAM w_param,
                                               LPARAM l_param) {
  // See comment in widget_win.h at the definition of WM_NCUAHDRAWCAPTION for
  // an explanation about why we need to handle this message.
  SetMsgHandled(delegate_->IsUsingCustomFrame());
  return 0;
}

LRESULT HWNDMessageHandler::OnNCUAHDrawFrame(UINT message,
                                             WPARAM w_param,
                                             LPARAM l_param) {
  // See comment in widget_win.h at the definition of WM_NCUAHDRAWCAPTION for
  // an explanation about why we need to handle this message.
  SetMsgHandled(delegate_->IsUsingCustomFrame());
  return 0;
}

LRESULT HWNDMessageHandler::OnNotify(int w_param, NMHDR* l_param) {
  LRESULT l_result = 0;
  SetMsgHandled(delegate_->HandleTooltipNotify(w_param, l_param, &l_result));
  return l_result;
}

void HWNDMessageHandler::OnPaint(HDC dc) {
  // Call BeginPaint()/EndPaint() around the paint handling, as that seems
  // to do more to actually validate the window's drawing region. This only
  // appears to matter for Windows that have the WS_EX_COMPOSITED style set
  // but will be valid in general too.
  PAINTSTRUCT ps;
  HDC display_dc = BeginPaint(hwnd(), &ps);
  CHECK(display_dc);

  // Try to paint accelerated first.
  if (!IsRectEmpty(&ps.rcPaint) &&
      !delegate_->HandlePaintAccelerated(gfx::Rect(ps.rcPaint))) {
    delegate_->HandlePaint(NULL);
  }

  EndPaint(hwnd(), &ps);
}

LRESULT HWNDMessageHandler::OnReflectedMessage(UINT message,
                                               WPARAM w_param,
                                               LPARAM l_param) {
  SetMsgHandled(FALSE);
  return 0;
}

LRESULT HWNDMessageHandler::OnScrollMessage(UINT message,
                                            WPARAM w_param,
                                            LPARAM l_param) {
  MSG msg = { hwnd(), message, w_param, l_param, GetMessageTime() };
  ui::ScrollEvent event(msg);
  delegate_->HandleScrollEvent(event);
  return 0;
}

void HWNDMessageHandler::OnSessionChange(WPARAM status_code,
                                         PWTSSESSION_NOTIFICATION session_id) {
  // Direct3D presents are ignored while the screen is locked, so force the
  // window to be redrawn on unlock.
  if (status_code == WTS_SESSION_UNLOCK)
    ForceRedrawWindow(10);

  SetMsgHandled(FALSE);
}

LRESULT HWNDMessageHandler::OnSetCursor(UINT message,
                                        WPARAM w_param,
                                        LPARAM l_param) {
  // Reimplement the necessary default behavior here. Calling DefWindowProc can
  // trigger weird non-client painting for non-glass windows with custom frames.
  // Using a ScopedRedrawLock to prevent caption rendering artifacts may allow
  // content behind this window to incorrectly paint in front of this window.
  // Invalidating the window to paint over either set of artifacts is not ideal.
  wchar_t* cursor = IDC_ARROW;
  switch (LOWORD(l_param)) {
    case HTSIZE:
      cursor = IDC_SIZENWSE;
      break;
    case HTLEFT:
    case HTRIGHT:
      cursor = IDC_SIZEWE;
      break;
    case HTTOP:
    case HTBOTTOM:
      cursor = IDC_SIZENS;
      break;
    case HTTOPLEFT:
    case HTBOTTOMRIGHT:
      cursor = IDC_SIZENWSE;
      break;
    case HTTOPRIGHT:
    case HTBOTTOMLEFT:
      cursor = IDC_SIZENESW;
      break;
    case HTCLIENT:
      SetCursor(current_cursor_);
      return 1;
    default:
      // Use the default value, IDC_ARROW.
      break;
  }
  ::SetCursor(LoadCursor(NULL, cursor));
  return 1;
}

void HWNDMessageHandler::OnSetFocus(HWND last_focused_window) {
  delegate_->HandleNativeFocus(last_focused_window);
  SetMsgHandled(FALSE);
}

LRESULT HWNDMessageHandler::OnSetIcon(UINT size_type, HICON new_icon) {
  // Use a ScopedRedrawLock to avoid weird non-client painting.
  return DefWindowProcWithRedrawLock(WM_SETICON, size_type,
                                     reinterpret_cast<LPARAM>(new_icon));
}

LRESULT HWNDMessageHandler::OnSetText(const wchar_t* text) {
  // Use a ScopedRedrawLock to avoid weird non-client painting.
  return DefWindowProcWithRedrawLock(WM_SETTEXT, NULL,
                                     reinterpret_cast<LPARAM>(text));
}

void HWNDMessageHandler::OnSettingChange(UINT flags, const wchar_t* section) {
  if (!GetParent(hwnd()) && (flags == SPI_SETWORKAREA) &&
      !delegate_->WillProcessWorkAreaChange()) {
    // Fire a dummy SetWindowPos() call, so we'll trip the code in
    // OnWindowPosChanging() below that notices work area changes.
    ::SetWindowPos(hwnd(), 0, 0, 0, 0, 0, SWP_NOSIZE | SWP_NOMOVE |
        SWP_NOZORDER | SWP_NOREDRAW | SWP_NOACTIVATE | SWP_NOOWNERZORDER);
    SetMsgHandled(TRUE);
  } else {
    if (flags == SPI_SETWORKAREA)
      delegate_->HandleWorkAreaChanged();
    SetMsgHandled(FALSE);
  }
}

void HWNDMessageHandler::OnSize(UINT param, const gfx::Size& size) {
  RedrawWindow(hwnd(), NULL, NULL, RDW_INVALIDATE | RDW_ALLCHILDREN);
  // ResetWindowRegion is going to trigger WM_NCPAINT. By doing it after we've
  // invoked OnSize we ensure the RootView has been laid out.
  ResetWindowRegion(false, true);

  // We add the WS_VSCROLL and WS_HSCROLL styles to top level windows to ensure
  // that legacy trackpad/trackpoint drivers generate the WM_VSCROLL and
  // WM_HSCROLL messages and scrolling works.
  // We want the scroll styles to be present on the window. However we don't
  // want Windows to draw the scrollbars. To achieve this we hide the scroll
  // bars and readd them to the window style in a posted task to ensure that we
  // don't get nested WM_SIZE messages.
  if (needs_scroll_styles_ && !in_size_loop_) {
    ShowScrollBar(hwnd(), SB_BOTH, FALSE);
    base::MessageLoop::current()->PostTask(
        FROM_HERE, base::Bind(&AddScrollStylesToWindow, hwnd()));
  }
}

void HWNDMessageHandler::OnSysCommand(UINT notification_code,
                                      const gfx::Point& point) {
  if (!delegate_->ShouldHandleSystemCommands())
    return;

  // Windows uses the 4 lower order bits of |notification_code| for type-
  // specific information so we must exclude this when comparing.
  static const int sc_mask = 0xFFF0;
  // Ignore size/move/maximize in fullscreen mode.
  if (fullscreen_handler_->fullscreen() &&
      (((notification_code & sc_mask) == SC_SIZE) ||
       ((notification_code & sc_mask) == SC_MOVE) ||
       ((notification_code & sc_mask) == SC_MAXIMIZE)))
    return;
  if (delegate_->IsUsingCustomFrame()) {
    if ((notification_code & sc_mask) == SC_MINIMIZE ||
        (notification_code & sc_mask) == SC_MAXIMIZE ||
        (notification_code & sc_mask) == SC_RESTORE) {
      delegate_->ResetWindowControls();
    } else if ((notification_code & sc_mask) == SC_MOVE ||
               (notification_code & sc_mask) == SC_SIZE) {
      if (!IsVisible()) {
        // Circumvent ScopedRedrawLocks and force visibility before entering a
        // resize or move modal loop to get continuous sizing/moving feedback.
        SetWindowLong(hwnd(), GWL_STYLE,
                      GetWindowLong(hwnd(), GWL_STYLE) | WS_VISIBLE);
      }
    }
  }

  // Handle SC_KEYMENU, which means that the user has pressed the ALT
  // key and released it, so we should focus the menu bar.
  if ((notification_code & sc_mask) == SC_KEYMENU && point.x() == 0) {
    int modifiers = ui::EF_NONE;
    if (base::win::IsShiftPressed())
      modifiers |= ui::EF_SHIFT_DOWN;
    if (base::win::IsCtrlPressed())
      modifiers |= ui::EF_CONTROL_DOWN;
    // Retrieve the status of shift and control keys to prevent consuming
    // shift+alt keys, which are used by Windows to change input languages.
    ui::Accelerator accelerator(ui::KeyboardCodeForWindowsKeyCode(VK_MENU),
                                modifiers);
    delegate_->HandleAccelerator(accelerator);
    return;
  }

  // If the delegate can't handle it, the system implementation will be called.
  if (!delegate_->HandleCommand(notification_code)) {
    // If the window is being resized by dragging the borders of the window
    // with the mouse/touch/keyboard, we flag as being in a size loop.
    if ((notification_code & sc_mask) == SC_SIZE)
      in_size_loop_ = true;
    base::WeakPtr<HWNDMessageHandler> ref(weak_factory_.GetWeakPtr());
    DefWindowProc(hwnd(), WM_SYSCOMMAND, notification_code,
                  MAKELPARAM(point.x(), point.y()));
    if (!ref.get())
      return;
    in_size_loop_ = false;
  }
}

void HWNDMessageHandler::OnThemeChanged() {
  ui::NativeThemeWin::instance()->CloseHandles();
}

LRESULT HWNDMessageHandler::OnTouchEvent(UINT message,
                                         WPARAM w_param,
                                         LPARAM l_param) {
  // Handle touch events only on Aura for now.
  int num_points = LOWORD(w_param);
  scoped_ptr<TOUCHINPUT[]> input(new TOUCHINPUT[num_points]);
  if (ui::GetTouchInputInfoWrapper(reinterpret_cast<HTOUCHINPUT>(l_param),
                                   num_points, input.get(),
                                   sizeof(TOUCHINPUT))) {
    int flags = ui::GetModifiersFromKeyState();
    TouchEvents touch_events;
    for (int i = 0; i < num_points; ++i) {
      POINT point;
      point.x = TOUCH_COORD_TO_PIXEL(input[i].x) /
                gfx::win::GetUndocumentedDPITouchScale();
      point.y = TOUCH_COORD_TO_PIXEL(input[i].y) /
                gfx::win::GetUndocumentedDPITouchScale();

      if (base::win::GetVersion() == base::win::VERSION_WIN7) {
        // Windows 7 sends touch events for touches in the non-client area,
        // whereas Windows 8 does not. In order to unify the behaviour, always
        // ignore touch events in the non-client area.
        LPARAM l_param_ht = MAKELPARAM(point.x, point.y);
        LRESULT hittest = SendMessage(hwnd(), WM_NCHITTEST, 0, l_param_ht);

        if (hittest != HTCLIENT)
          return 0;
      }

      ScreenToClient(hwnd(), &point);

      last_touch_message_time_ = ::GetMessageTime();

      ui::EventType touch_event_type = ui::ET_UNKNOWN;

      if (input[i].dwFlags & TOUCHEVENTF_DOWN) {
        touch_ids_.insert(input[i].dwID);
        touch_event_type = ui::ET_TOUCH_PRESSED;
        touch_down_context_ = true;
        base::MessageLoop::current()->PostDelayedTask(
            FROM_HERE,
            base::Bind(&HWNDMessageHandler::ResetTouchDownContext,
                       weak_factory_.GetWeakPtr()),
            base::TimeDelta::FromMilliseconds(kTouchDownContextResetTimeout));
      } else if (input[i].dwFlags & TOUCHEVENTF_UP) {
        touch_ids_.erase(input[i].dwID);
        touch_event_type = ui::ET_TOUCH_RELEASED;
      } else if (input[i].dwFlags & TOUCHEVENTF_MOVE) {
        touch_event_type = ui::ET_TOUCH_MOVED;
      }
      if (touch_event_type != ui::ET_UNKNOWN) {
        base::TimeTicks now;
        // input[i].dwTime doesn't necessarily relate to the system time at all,
        // so use base::TimeTicks::HighResNow() if possible, or
        // base::TimeTicks::Now() otherwise.
        if (base::TimeTicks::IsHighResNowFastAndReliable())
          now = base::TimeTicks::HighResNow();
        else
          now = base::TimeTicks::Now();
        ui::TouchEvent event(touch_event_type,
                             gfx::Point(point.x, point.y),
                             id_generator_.GetGeneratedID(input[i].dwID),
                             now - base::TimeTicks());
        event.set_flags(flags);
        event.latency()->AddLatencyNumberWithTimestamp(
            ui::INPUT_EVENT_LATENCY_ORIGINAL_COMPONENT,
            0,
            0,
            base::TimeTicks::FromInternalValue(
                event.time_stamp().ToInternalValue()),
            1);

        touch_events.push_back(event);
        if (touch_event_type == ui::ET_TOUCH_RELEASED)
          id_generator_.ReleaseNumber(input[i].dwID);
      }
    }
    // Handle the touch events asynchronously. We need this because touch
    // events on windows don't fire if we enter a modal loop in the context of
    // a touch event.
    base::MessageLoop::current()->PostTask(
        FROM_HERE,
        base::Bind(&HWNDMessageHandler::HandleTouchEvents,
                   weak_factory_.GetWeakPtr(), touch_events));
  }
  CloseTouchInputHandle(reinterpret_cast<HTOUCHINPUT>(l_param));
  SetMsgHandled(FALSE);
  return 0;
}

void HWNDMessageHandler::OnWindowPosChanging(WINDOWPOS* window_pos) {
  if (ignore_window_pos_changes_) {
    // If somebody's trying to toggle our visibility, change the nonclient area,
    // change our Z-order, or activate us, we should probably let it go through.
    if (!(window_pos->flags & ((IsVisible() ? SWP_HIDEWINDOW : SWP_SHOWWINDOW) |
        SWP_FRAMECHANGED)) &&
        (window_pos->flags & (SWP_NOZORDER | SWP_NOACTIVATE))) {
      // Just sizing/moving the window; ignore.
      window_pos->flags |= SWP_NOSIZE | SWP_NOMOVE | SWP_NOREDRAW;
      window_pos->flags &= ~(SWP_SHOWWINDOW | SWP_HIDEWINDOW);
    }
  } else if (!GetParent(hwnd())) {
    RECT window_rect;
    HMONITOR monitor;
    gfx::Rect monitor_rect, work_area;
    if (GetWindowRect(hwnd(), &window_rect) &&
        GetMonitorAndRects(window_rect, &monitor, &monitor_rect, &work_area)) {
      bool work_area_changed = (monitor_rect == last_monitor_rect_) &&
                               (work_area != last_work_area_);
      if (monitor && (monitor == last_monitor_) &&
          ((fullscreen_handler_->fullscreen() &&
            !fullscreen_handler_->metro_snap()) ||
            work_area_changed)) {
        // A rect for the monitor we're on changed.  Normally Windows notifies
        // us about this (and thus we're reaching here due to the SetWindowPos()
        // call in OnSettingChange() above), but with some software (e.g.
        // nVidia's nView desktop manager) the work area can change asynchronous
        // to any notification, and we're just sent a SetWindowPos() call with a
        // new (frequently incorrect) position/size.  In either case, the best
        // response is to throw away the existing position/size information in
        // |window_pos| and recalculate it based on the new work rect.
        gfx::Rect new_window_rect;
        if (fullscreen_handler_->fullscreen()) {
          new_window_rect = monitor_rect;
        } else if (IsMaximized()) {
          new_window_rect = work_area;
          int border_thickness = GetSystemMetrics(SM_CXSIZEFRAME);
          new_window_rect.Inset(-border_thickness, -border_thickness);
        } else {
          new_window_rect = gfx::Rect(window_rect);
          new_window_rect.AdjustToFit(work_area);
        }
        window_pos->x = new_window_rect.x();
        window_pos->y = new_window_rect.y();
        window_pos->cx = new_window_rect.width();
        window_pos->cy = new_window_rect.height();
        // WARNING!  Don't set SWP_FRAMECHANGED here, it breaks moving the child
        // HWNDs for some reason.
        window_pos->flags &= ~(SWP_NOSIZE | SWP_NOMOVE | SWP_NOREDRAW);
        window_pos->flags |= SWP_NOCOPYBITS;

        // Now ignore all immediately-following SetWindowPos() changes.  Windows
        // likes to (incorrectly) recalculate what our position/size should be
        // and send us further updates.
        ignore_window_pos_changes_ = true;
        base::MessageLoop::current()->PostTask(
            FROM_HERE,
            base::Bind(&HWNDMessageHandler::StopIgnoringPosChanges,
                       weak_factory_.GetWeakPtr()));
      }
      last_monitor_ = monitor;
      last_monitor_rect_ = monitor_rect;
      last_work_area_ = work_area;
    }
  }

  if (ScopedFullscreenVisibility::IsHiddenForFullscreen(hwnd())) {
    // Prevent the window from being made visible if we've been asked to do so.
    // See comment in header as to why we might want this.
    window_pos->flags &= ~SWP_SHOWWINDOW;
  }

  if (window_pos->flags & SWP_SHOWWINDOW)
    delegate_->HandleVisibilityChanging(true);
  else if (window_pos->flags & SWP_HIDEWINDOW)
    delegate_->HandleVisibilityChanging(false);

  SetMsgHandled(FALSE);
}

void HWNDMessageHandler::OnWindowPosChanged(WINDOWPOS* window_pos) {
  if (DidClientAreaSizeChange(window_pos))
    ClientAreaSizeChanged();
  if (remove_standard_frame_ && window_pos->flags & SWP_FRAMECHANGED &&
      ui::win::IsAeroGlassEnabled() &&
      (window_ex_style() & WS_EX_COMPOSITED) == 0) {
    MARGINS m = {10, 10, 10, 10};
    DwmExtendFrameIntoClientArea(hwnd(), &m);
  }
  if (window_pos->flags & SWP_SHOWWINDOW)
    delegate_->HandleVisibilityChanged(true);
  else if (window_pos->flags & SWP_HIDEWINDOW)
    delegate_->HandleVisibilityChanged(false);
  SetMsgHandled(FALSE);
}

void HWNDMessageHandler::HandleTouchEvents(const TouchEvents& touch_events) {
  base::WeakPtr<HWNDMessageHandler> ref(weak_factory_.GetWeakPtr());
  for (size_t i = 0; i < touch_events.size() && ref; ++i)
    delegate_->HandleTouchEvent(touch_events[i]);
}

void HWNDMessageHandler::ResetTouchDownContext() {
  touch_down_context_ = false;
}

LRESULT HWNDMessageHandler::HandleMouseEventInternal(UINT message,
                                                     WPARAM w_param,
                                                     LPARAM l_param,
                                                     bool track_mouse) {
  if (!touch_ids_.empty())
    return 0;
  // We handle touch events on Windows Aura. Windows generates synthesized
  // mouse messages in response to touch which we should ignore. However touch
  // messages are only received for the client area. We need to ignore the
  // synthesized mouse messages for all points in the client area and places
  // which return HTNOWHERE.
  if (ui::IsMouseEventFromTouch(message)) {
    LPARAM l_param_ht = l_param;
    // For mouse events (except wheel events), location is in window coordinates
    // and should be converted to screen coordinates for WM_NCHITTEST.
    if (message != WM_MOUSEWHEEL && message != WM_MOUSEHWHEEL) {
      POINT screen_point = CR_POINT_INITIALIZER_FROM_LPARAM(l_param_ht);
      MapWindowPoints(hwnd(), HWND_DESKTOP, &screen_point, 1);
      l_param_ht = MAKELPARAM(screen_point.x, screen_point.y);
    }
    LRESULT hittest = SendMessage(hwnd(), WM_NCHITTEST, 0, l_param_ht);
    if (hittest == HTCLIENT || hittest == HTNOWHERE)
      return 0;
  }

  if (message == WM_RBUTTONUP && is_right_mouse_pressed_on_caption_) {
    is_right_mouse_pressed_on_caption_ = false;
    ReleaseCapture();
    // |point| is in window coordinates, but WM_NCHITTEST and TrackPopupMenu()
    // expect screen coordinates.
    POINT screen_point = CR_POINT_INITIALIZER_FROM_LPARAM(l_param);
    MapWindowPoints(hwnd(), HWND_DESKTOP, &screen_point, 1);
    w_param = SendMessage(hwnd(), WM_NCHITTEST, 0,
                          MAKELPARAM(screen_point.x, screen_point.y));
    if (w_param == HTCAPTION || w_param == HTSYSMENU) {
      gfx::ShowSystemMenuAtPoint(hwnd(), gfx::Point(screen_point));
      return 0;
    }
  } else if (message == WM_NCLBUTTONDOWN && delegate_->IsUsingCustomFrame()) {
    switch (w_param) {
      case HTCLOSE:
      case HTMINBUTTON:
      case HTMAXBUTTON: {
        // When the mouse is pressed down in these specific non-client areas,
        // we need to tell the RootView to send the mouse pressed event (which
        // sets capture, allowing subsequent WM_LBUTTONUP (note, _not_
        // WM_NCLBUTTONUP) to fire so that the appropriate WM_SYSCOMMAND can be
        // sent by the applicable button's ButtonListener. We _have_ to do this
        // way rather than letting Windows just send the syscommand itself (as
        // would happen if we never did this dance) because for some insane
        // reason DefWindowProc for WM_NCLBUTTONDOWN also renders the pressed
        // window control button appearance, in the Windows classic style, over
        // our view! Ick! By handling this message we prevent Windows from
        // doing this undesirable thing, but that means we need to roll the
        // sys-command handling ourselves.
        // Combine |w_param| with common key state message flags.
        w_param |= base::win::IsCtrlPressed() ? MK_CONTROL : 0;
        w_param |= base::win::IsShiftPressed() ? MK_SHIFT : 0;
      }
    }
  } else if (message == WM_NCRBUTTONDOWN &&
      (w_param == HTCAPTION || w_param == HTSYSMENU)) {
    is_right_mouse_pressed_on_caption_ = true;
    // We SetCapture() to ensure we only show the menu when the button
    // down and up are both on the caption. Note: this causes the button up to
    // be WM_RBUTTONUP instead of WM_NCRBUTTONUP.
    SetCapture();
  }
  long message_time = GetMessageTime();
  MSG msg = { hwnd(), message, w_param, l_param, message_time,
              { CR_GET_X_LPARAM(l_param), CR_GET_Y_LPARAM(l_param) } };
  ui::MouseEvent event(msg);
  if (IsSynthesizedMouseMessage(message, message_time, l_param))
    event.set_flags(event.flags() | ui::EF_FROM_TOUCH);

  if (!(event.flags() & ui::EF_IS_NON_CLIENT))
    delegate_->HandleTooltipMouseMove(message, w_param, l_param);

  if (event.type() == ui::ET_MOUSE_MOVED && !HasCapture() && track_mouse) {
    // Windows only fires WM_MOUSELEAVE events if the application begins
    // "tracking" mouse events for a given HWND during WM_MOUSEMOVE events.
    // We need to call |TrackMouseEvents| to listen for WM_MOUSELEAVE.
    TrackMouseEvents((message == WM_NCMOUSEMOVE) ?
        TME_NONCLIENT | TME_LEAVE : TME_LEAVE);
  } else if (event.type() == ui::ET_MOUSE_EXITED) {
    // Reset our tracking flags so future mouse movement over this
    // NativeWidget results in a new tracking session. Fall through for
    // OnMouseEvent.
    active_mouse_tracking_flags_ = 0;
  } else if (event.type() == ui::ET_MOUSEWHEEL) {
    // Reroute the mouse wheel to the window under the pointer if applicable.
    return (ui::RerouteMouseWheel(hwnd(), w_param, l_param) ||
            delegate_->HandleMouseEvent(ui::MouseWheelEvent(msg))) ? 0 : 1;
  }

  // There are cases where the code handling the message destroys the window,
  // so use the weak ptr to check if destruction occured or not.
  base::WeakPtr<HWNDMessageHandler> ref(weak_factory_.GetWeakPtr());
  bool handled = delegate_->HandleMouseEvent(event);
  if (!ref.get())
    return 0;
  if (!handled && message == WM_NCLBUTTONDOWN && w_param != HTSYSMENU &&
      delegate_->IsUsingCustomFrame()) {
    // TODO(msw): Eliminate undesired painting, or re-evaluate this workaround.
    // DefWindowProc for WM_NCLBUTTONDOWN does weird non-client painting, so we
    // need to call it inside a ScopedRedrawLock. This may cause other negative
    // side-effects (ex/ stifling non-client mouse releases).
    DefWindowProcWithRedrawLock(message, w_param, l_param);
    handled = true;
  }

  if (ref.get())
    SetMsgHandled(handled);
  return 0;
}

bool HWNDMessageHandler::IsSynthesizedMouseMessage(unsigned int message,
                                                   int message_time,
                                                   LPARAM l_param) {
  if (ui::IsMouseEventFromTouch(message))
    return true;
  // Ignore mouse messages which occur at the same location as the current
  // cursor position and within a time difference of 500 ms from the last
  // touch message.
  if (last_touch_message_time_ && message_time >= last_touch_message_time_ &&
      ((message_time - last_touch_message_time_) <=
          kSynthesizedMouseTouchMessagesTimeDifference)) {
    POINT mouse_location = CR_POINT_INITIALIZER_FROM_LPARAM(l_param);
    ::ClientToScreen(hwnd(), &mouse_location);
    POINT cursor_pos = {0};
    ::GetCursorPos(&cursor_pos);
    if (memcmp(&cursor_pos, &mouse_location, sizeof(POINT)))
      return false;
    return true;
  }
  return false;
}

}  // namespace views