root/content/child/npapi/webplugin_delegate_impl_win.cc

DEFINITIONS

1. disposable_dc_
2. GetKeyPath
3. GetPluginMajorVersion
4. HandleEventMessageFilterHook
5. MouseHookProc
6. creation_succeeded_
7. PlatformInitialize
8. PlatformDestroyInstance
9. Paint
10. WindowedCreatePlugin
11. WindowedDestroyWindow
12. ClearThrottleQueueForWindow
13. OnThrottleMessage
14. ThrottleMessage
15. FlashWindowlessWndProc
16. DummyWindowProc
17. EnumFlashWindows
18. CreateDummyWindowForActivation
19. WindowedReposition
20. WindowedSetWindow
21. RegisterNativeWindowClass
22. WrapperWindowProc
23. IsUserGestureMessage
24. NativeWndProc
25. WindowlessUpdateGeometry
26. WindowlessPaint
27. WindowlessSetWindow
28. PlatformSetPluginHasFocus
29. NPEventFromWebMouseEvent
30. NPEventFromWebKeyboardEvent
31. NPEventFromWebInputEvent
32. PlatformHandleInputEvent
33. OnModalLoopEntered
34. ShouldTrackEventForModalLoops
35. OnUserGestureEnd
36. TrackPopupMenuPatch
37. SetCursorPatch
38. RegEnumKeyExWPatch
39. ImeCompositionUpdated
40. ImeCompositionCompleted
41. GetIMEStatus
42. GetProcAddressPatch
43. WindowFromPointPatch
44. HandleCaptureForMessage

// 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 "content/child/npapi/webplugin_delegate_impl.h"

#include <map>
#include <set>
#include <string>
#include <vector>

#include "base/bind.h"
#include "base/compiler_specific.h"
#include "base/lazy_instance.h"
#include "base/memory/scoped_ptr.h"
#include "base/message_loop/message_loop.h"
#include "base/metrics/stats_counters.h"
#include "base/strings/string_util.h"
#include "base/strings/stringprintf.h"
#include "base/synchronization/lock.h"
#include "base/version.h"
#include "base/win/iat_patch_function.h"
#include "base/win/registry.h"
#include "base/win/windows_version.h"
#include "content/child/npapi/plugin_instance.h"
#include "content/child/npapi/plugin_lib.h"
#include "content/child/npapi/plugin_stream_url.h"
#include "content/child/npapi/webplugin.h"
#include "content/child/npapi/webplugin_ime_win.h"
#include "content/common/cursors/webcursor.h"
#include "content/common/plugin_constants_win.h"
#include "content/public/common/content_constants.h"
#include "skia/ext/platform_canvas.h"
#include "third_party/WebKit/public/web/WebInputEvent.h"
#include "ui/gfx/win/dpi.h"
#include "ui/gfx/win/hwnd_util.h"

using blink::WebKeyboardEvent;
using blink::WebInputEvent;
using blink::WebMouseEvent;

namespace content {

namespace {

const wchar_t kWebPluginDelegateProperty[] = L"WebPluginDelegateProperty";
const wchar_t kPluginFlashThrottle[] = L"FlashThrottle";

// The fastest we are willing to process WM_USER+1 events for Flash.
// Flash can easily exceed the limits of our CPU if we don't throttle it.
// The throttle has been chosen by testing various delays and compromising
// on acceptable Flash performance and reasonable CPU consumption.
//
// I'd like to make the throttle delay variable, based on the amount of
// time currently required to paint Flash plugins.  There isn't a good
// way to count the time spent in aggregate plugin painting, however, so
// this seems to work well enough.
const int kFlashWMUSERMessageThrottleDelayMs = 5;

// Flash displays popups in response to user clicks by posting a WM_USER
// message to the plugin window. The handler for this message displays
// the popup. To ensure that the popups allowed state is sent correctly
// to the renderer we reset the popups allowed state in a timer.
const int kWindowedPluginPopupTimerMs = 50;

// The current instance of the plugin which entered the modal loop.
WebPluginDelegateImpl* g_current_plugin_instance = NULL;

typedef std::deque<MSG> ThrottleQueue;
base::LazyInstance<ThrottleQueue> g_throttle_queue = LAZY_INSTANCE_INITIALIZER;

base::LazyInstance<std::map<HWND, WNDPROC> > g_window_handle_proc_map =
    LAZY_INSTANCE_INITIALIZER;

// Helper object for patching the TrackPopupMenu API.
base::LazyInstance<base::win::IATPatchFunction> g_iat_patch_track_popup_menu =
    LAZY_INSTANCE_INITIALIZER;

// Helper object for patching the SetCursor API.
base::LazyInstance<base::win::IATPatchFunction> g_iat_patch_set_cursor =
    LAZY_INSTANCE_INITIALIZER;

// Helper object for patching the RegEnumKeyExW API.
base::LazyInstance<base::win::IATPatchFunction> g_iat_patch_reg_enum_key_ex_w =
    LAZY_INSTANCE_INITIALIZER;

// Helper object for patching the GetProcAddress API.
base::LazyInstance<base::win::IATPatchFunction> g_iat_patch_get_proc_address =
    LAZY_INSTANCE_INITIALIZER;

base::LazyInstance<base::win::IATPatchFunction> g_iat_patch_window_from_point =
    LAZY_INSTANCE_INITIALIZER;

// http://crbug.com/16114
// Enforces providing a valid device context in NPWindow, so that NPP_SetWindow
// is never called with NPNWindoTypeDrawable and NPWindow set to NULL.
// Doing so allows removing NPP_SetWindow call during painting a windowless
// plugin, which otherwise could trigger layout change while painting by
// invoking NPN_Evaluate. Which would cause bad, bad crashes. Bad crashes.
// TODO(dglazkov): If this approach doesn't produce regressions, move class to
// webplugin_delegate_impl.h and implement for other platforms.
class DrawableContextEnforcer {
 public:
  explicit DrawableContextEnforcer(NPWindow* window)
      : window_(window),
        disposable_dc_(window && !window->window) {
    // If NPWindow is NULL, create a device context with monochrome 1x1 surface
    // and stuff it to NPWindow.
    if (disposable_dc_)
      window_->window = CreateCompatibleDC(NULL);
  }

  ~DrawableContextEnforcer() {
    if (!disposable_dc_)
      return;

    DeleteDC(static_cast<HDC>(window_->window));
    window_->window = NULL;
  }

 private:
  NPWindow* window_;
  bool disposable_dc_;
};

// These are from ntddk.h
typedef LONG NTSTATUS;

#ifndef STATUS_SUCCESS
#define STATUS_SUCCESS ((NTSTATUS)0x00000000L)
#endif

#ifndef STATUS_BUFFER_TOO_SMALL
#define STATUS_BUFFER_TOO_SMALL ((NTSTATUS)0xC0000023L)
#endif

typedef enum _KEY_INFORMATION_CLASS {
  KeyBasicInformation,
  KeyNodeInformation,
  KeyFullInformation,
  KeyNameInformation,
  KeyCachedInformation,
  KeyVirtualizationInformation
} KEY_INFORMATION_CLASS;

typedef struct _KEY_NAME_INFORMATION {
  ULONG NameLength;
  WCHAR Name[1];
} KEY_NAME_INFORMATION, *PKEY_NAME_INFORMATION;

typedef DWORD (__stdcall *ZwQueryKeyType)(
    HANDLE  key_handle,
    int key_information_class,
    PVOID  key_information,
    ULONG  length,
    PULONG  result_length);

// Returns a key's full path.
std::wstring GetKeyPath(HKEY key) {
  if (key == NULL)
    return L"";

  HMODULE dll = GetModuleHandle(L"ntdll.dll");
  if (dll == NULL)
    return L"";

  ZwQueryKeyType func = reinterpret_cast<ZwQueryKeyType>(
      ::GetProcAddress(dll, "ZwQueryKey"));
  if (func == NULL)
    return L"";

  DWORD size = 0;
  DWORD result = 0;
  result = func(key, KeyNameInformation, 0, 0, &size);
  if (result != STATUS_BUFFER_TOO_SMALL)
    return L"";

  scoped_ptr<char[]> buffer(new char[size]);
  if (buffer.get() == NULL)
    return L"";

  result = func(key, KeyNameInformation, buffer.get(), size, &size);
  if (result != STATUS_SUCCESS)
    return L"";

  KEY_NAME_INFORMATION* info =
      reinterpret_cast<KEY_NAME_INFORMATION*>(buffer.get());
  return std::wstring(info->Name, info->NameLength / sizeof(wchar_t));
}

int GetPluginMajorVersion(const WebPluginInfo& plugin_info) {
  Version plugin_version;
  WebPluginInfo::CreateVersionFromString(plugin_info.version, &plugin_version);

  int major_version = 0;
  if (plugin_version.IsValid())
    major_version = plugin_version.components()[0];

  return major_version;
}

}  // namespace

LRESULT CALLBACK WebPluginDelegateImpl::HandleEventMessageFilterHook(
    int code, WPARAM wParam, LPARAM lParam) {
  if (g_current_plugin_instance) {
    g_current_plugin_instance->OnModalLoopEntered();
  } else {
    NOTREACHED();
  }
  return CallNextHookEx(NULL, code, wParam, lParam);
}

LRESULT CALLBACK WebPluginDelegateImpl::MouseHookProc(
    int code, WPARAM wParam, LPARAM lParam) {
  if (code == HC_ACTION) {
    MOUSEHOOKSTRUCT* hook_struct = reinterpret_cast<MOUSEHOOKSTRUCT*>(lParam);
    if (hook_struct)
      HandleCaptureForMessage(hook_struct->hwnd, wParam);
  }

  return CallNextHookEx(NULL, code, wParam, lParam);
}

WebPluginDelegateImpl::WebPluginDelegateImpl(
    WebPlugin* plugin,
    PluginInstance* instance)
    : instance_(instance),
      quirks_(0),
      plugin_(plugin),
      windowless_(false),
      windowed_handle_(NULL),
      windowed_did_set_window_(false),
      plugin_wnd_proc_(NULL),
      last_message_(0),
      is_calling_wndproc(false),
      dummy_window_for_activation_(NULL),
      dummy_window_parent_(NULL),
      old_dummy_window_proc_(NULL),
      handle_event_message_filter_hook_(NULL),
      handle_event_pump_messages_event_(NULL),
      user_gesture_message_posted_(false),
      user_gesture_msg_factory_(this),
      handle_event_depth_(0),
      mouse_hook_(NULL),
      first_set_window_call_(true),
      plugin_has_focus_(false),
      has_webkit_focus_(false),
      containing_view_has_focus_(true),
      creation_succeeded_(false) {
  memset(&window_, 0, sizeof(window_));

  const WebPluginInfo& plugin_info = instance_->plugin_lib()->plugin_info();
  std::wstring filename =
      StringToLowerASCII(plugin_info.path.BaseName().value());

  if (instance_->mime_type() == kFlashPluginSwfMimeType ||
      filename == kFlashPlugin) {
    // Flash only requests windowless plugins if we return a Mozilla user
    // agent.
    instance_->set_use_mozilla_user_agent();
    quirks_ |= PLUGIN_QUIRK_THROTTLE_WM_USER_PLUS_ONE;
    quirks_ |= PLUGIN_QUIRK_PATCH_SETCURSOR;
    quirks_ |= PLUGIN_QUIRK_ALWAYS_NOTIFY_SUCCESS;
    quirks_ |= PLUGIN_QUIRK_HANDLE_MOUSE_CAPTURE;
    quirks_ |= PLUGIN_QUIRK_EMULATE_IME;
    quirks_ |= PLUGIN_QUIRK_FAKE_WINDOW_FROM_POINT;
  } else if (filename == kAcrobatReaderPlugin) {
    // Check for the version number above or equal 9.
    int major_version = GetPluginMajorVersion(plugin_info);
    if (major_version >= 9) {
      quirks_ |= PLUGIN_QUIRK_DIE_AFTER_UNLOAD;
      // 9.2 needs this.
      quirks_ |= PLUGIN_QUIRK_SETWINDOW_TWICE;
    }
    quirks_ |= PLUGIN_QUIRK_BLOCK_NONSTANDARD_GETURL_REQUESTS;
  } else if (plugin_info.name.find(L"Windows Media Player") !=
             std::wstring::npos) {
    // Windows Media Player needs two NPP_SetWindow calls.
    quirks_ |= PLUGIN_QUIRK_SETWINDOW_TWICE;

    // Windowless mode doesn't work in the WMP NPAPI plugin.
    quirks_ |= PLUGIN_QUIRK_NO_WINDOWLESS;

    // The media player plugin sets its size on the first NPP_SetWindow call
    // and never updates its size. We should call the underlying NPP_SetWindow
    // only when we have the correct size.
    quirks_ |= PLUGIN_QUIRK_IGNORE_FIRST_SETWINDOW_CALL;

    if (filename == kOldWMPPlugin) {
      // Non-admin users on XP couldn't modify the key to force the new UI.
      quirks_ |= PLUGIN_QUIRK_PATCH_REGENUMKEYEXW;
    }
  } else if (instance_->mime_type() == "audio/x-pn-realaudio-plugin" ||
             filename == kRealPlayerPlugin) {
    quirks_ |= PLUGIN_QUIRK_DONT_CALL_WND_PROC_RECURSIVELY;
  } else if (plugin_info.name.find(L"VLC Multimedia Plugin") !=
             std::wstring::npos ||
             plugin_info.name.find(L"VLC Multimedia Plug-in") !=
             std::wstring::npos) {
    // VLC hangs on NPP_Destroy if we call NPP_SetWindow with a null window
    // handle
    quirks_ |= PLUGIN_QUIRK_DONT_SET_NULL_WINDOW_HANDLE_ON_DESTROY;
    int major_version = GetPluginMajorVersion(plugin_info);
    if (major_version == 0) {
      // VLC 0.8.6d and 0.8.6e crash if multiple instances are created.
      quirks_ |= PLUGIN_QUIRK_DONT_ALLOW_MULTIPLE_INSTANCES;
    }
  } else if (filename == kSilverlightPlugin) {
    // Explanation for this quirk can be found in
    // WebPluginDelegateImpl::Initialize.
    quirks_ |= PLUGIN_QUIRK_PATCH_SETCURSOR;
  } else if (plugin_info.name.find(L"DivX Web Player") !=
             std::wstring::npos) {
    // The divx plugin sets its size on the first NPP_SetWindow call and never
    // updates its size. We should call the underlying NPP_SetWindow only when
    // we have the correct size.
    quirks_ |= PLUGIN_QUIRK_IGNORE_FIRST_SETWINDOW_CALL;
  }
}

WebPluginDelegateImpl::~WebPluginDelegateImpl() {
  if (::IsWindow(dummy_window_for_activation_)) {
    WNDPROC current_wnd_proc = reinterpret_cast<WNDPROC>(
        GetWindowLongPtr(dummy_window_for_activation_, GWLP_WNDPROC));
    if (current_wnd_proc == DummyWindowProc) {
      SetWindowLongPtr(dummy_window_for_activation_,
                       GWLP_WNDPROC,
                       reinterpret_cast<LONG_PTR>(old_dummy_window_proc_));
    }
    ::DestroyWindow(dummy_window_for_activation_);
  }

  DestroyInstance();

  if (!windowless_)
    WindowedDestroyWindow();

  if (handle_event_pump_messages_event_) {
    CloseHandle(handle_event_pump_messages_event_);
  }
}

bool WebPluginDelegateImpl::PlatformInitialize() {
  plugin_->SetWindow(windowed_handle_);

  if (windowless_) {
    CreateDummyWindowForActivation();
    handle_event_pump_messages_event_ = CreateEvent(NULL, TRUE, FALSE, NULL);
    plugin_->SetWindowlessData(
        handle_event_pump_messages_event_,
        reinterpret_cast<gfx::NativeViewId>(dummy_window_for_activation_));
  }

  // Windowless plugins call the WindowFromPoint API and passes the result of
  // that to the TrackPopupMenu API call as the owner window. This causes the
  // API to fail as the API expects the window handle to live on the same
  // thread as the caller. It works in the other browsers as the plugin lives
  // on the browser thread. Our workaround is to intercept the TrackPopupMenu
  // API and replace the window handle with the dummy activation window.
  if (windowless_ && !g_iat_patch_track_popup_menu.Pointer()->is_patched()) {
    g_iat_patch_track_popup_menu.Pointer()->Patch(
        GetPluginPath().value().c_str(), "user32.dll", "TrackPopupMenu",
        WebPluginDelegateImpl::TrackPopupMenuPatch);
  }

  // Windowless plugins can set cursors by calling the SetCursor API. This
  // works because the thread inputs of the browser UI thread and the plugin
  // thread are attached. We intercept the SetCursor API for windowless
  // plugins and remember the cursor being set. This is shipped over to the
  // browser in the HandleEvent call, which ensures that the cursor does not
  // change when a windowless plugin instance changes the cursor
  // in a background tab.
  if (windowless_ && !g_iat_patch_set_cursor.Pointer()->is_patched() &&
      (quirks_ & PLUGIN_QUIRK_PATCH_SETCURSOR)) {
    g_iat_patch_set_cursor.Pointer()->Patch(
        GetPluginPath().value().c_str(), "user32.dll", "SetCursor",
        WebPluginDelegateImpl::SetCursorPatch);
  }

  // The windowed flash plugin has a bug which occurs when the plugin enters
  // fullscreen mode. It basically captures the mouse on WM_LBUTTONDOWN and
  // does not release capture correctly causing it to stop receiving
  // subsequent mouse events. This problem is also seen in Safari where there
  // is code to handle this in the wndproc. However the plugin subclasses the
  // window again in WM_LBUTTONDOWN before entering full screen. As a result
  // Safari does not receive the WM_LBUTTONUP message. To workaround this
  // issue we use a per thread mouse hook. This bug does not occur in Firefox
  // and opera. Firefox has code similar to Safari. It could well be a bug in
  // the flash plugin, which only occurs in webkit based browsers.
  if (quirks_ & PLUGIN_QUIRK_HANDLE_MOUSE_CAPTURE) {
    mouse_hook_ = SetWindowsHookEx(WH_MOUSE, MouseHookProc, NULL,
                                    GetCurrentThreadId());
  }

  // On XP, WMP will use its old UI unless a registry key under HKLM has the
  // name of the current process.  We do it in the installer for admin users,
  // for the rest patch this function.
  if ((quirks_ & PLUGIN_QUIRK_PATCH_REGENUMKEYEXW) &&
      base::win::GetVersion() == base::win::VERSION_XP &&
      (base::win::RegKey().Open(HKEY_LOCAL_MACHINE,
          L"SOFTWARE\\Microsoft\\MediaPlayer\\ShimInclusionList\\chrome.exe",
          KEY_READ) != ERROR_SUCCESS) &&
      !g_iat_patch_reg_enum_key_ex_w.Pointer()->is_patched()) {
    g_iat_patch_reg_enum_key_ex_w.Pointer()->Patch(
        L"wmpdxm.dll", "advapi32.dll", "RegEnumKeyExW",
        WebPluginDelegateImpl::RegEnumKeyExWPatch);
  }

  // Flash retrieves the pointers to IMM32 functions with GetProcAddress() calls
  // and use them to retrieve IME data. We add a patch to this function so we
  // can dispatch these IMM32 calls to the WebPluginIMEWin class, which emulates
  // IMM32 functions for Flash.
  if (!g_iat_patch_get_proc_address.Pointer()->is_patched() &&
      (quirks_ & PLUGIN_QUIRK_EMULATE_IME)) {
    g_iat_patch_get_proc_address.Pointer()->Patch(
        GetPluginPath().value().c_str(), "kernel32.dll", "GetProcAddress",
        GetProcAddressPatch);
  }

  if (windowless_ && !g_iat_patch_window_from_point.Pointer()->is_patched() &&
      (quirks_ & PLUGIN_QUIRK_FAKE_WINDOW_FROM_POINT)) {
    g_iat_patch_window_from_point.Pointer()->Patch(
        GetPluginPath().value().c_str(), "user32.dll", "WindowFromPoint",
        WebPluginDelegateImpl::WindowFromPointPatch);
  }

  return true;
}

void WebPluginDelegateImpl::PlatformDestroyInstance() {
  if (!instance_->plugin_lib())
    return;

  // Unpatch if this is the last plugin instance.
  if (instance_->plugin_lib()->instance_count() != 1)
    return;

  if (g_iat_patch_set_cursor.Pointer()->is_patched())
    g_iat_patch_set_cursor.Pointer()->Unpatch();

  if (g_iat_patch_track_popup_menu.Pointer()->is_patched())
    g_iat_patch_track_popup_menu.Pointer()->Unpatch();

  if (g_iat_patch_reg_enum_key_ex_w.Pointer()->is_patched())
    g_iat_patch_reg_enum_key_ex_w.Pointer()->Unpatch();

  if (g_iat_patch_window_from_point.Pointer()->is_patched())
    g_iat_patch_window_from_point.Pointer()->Unpatch();

  if (mouse_hook_) {
    UnhookWindowsHookEx(mouse_hook_);
    mouse_hook_ = NULL;
  }
}

void WebPluginDelegateImpl::Paint(SkCanvas* canvas, const gfx::Rect& rect) {
  if (windowless_ && skia::SupportsPlatformPaint(canvas)) {
    skia::ScopedPlatformPaint scoped_platform_paint(canvas);
    HDC hdc = scoped_platform_paint.GetPlatformSurface();
    WindowlessPaint(hdc, rect);
  }
}

bool WebPluginDelegateImpl::WindowedCreatePlugin() {
  DCHECK(!windowed_handle_);

  RegisterNativeWindowClass();

  // The window will be sized and shown later.
  windowed_handle_ = CreateWindowEx(
      WS_EX_LEFT | WS_EX_LTRREADING | WS_EX_RIGHTSCROLLBAR,
      kNativeWindowClassName,
      0,
      WS_POPUP | WS_CLIPCHILDREN | WS_CLIPSIBLINGS,
      0,
      0,
      0,
      0,
      GetDesktopWindow(),
      0,
      GetModuleHandle(NULL),
      0);
  if (windowed_handle_ == 0)
    return false;

    // This is a tricky workaround for Issue 2673 in chromium "Flash: IME not
    // available". To use IMEs in this window, we have to make Windows attach
  // IMEs to this window (i.e. load IME DLLs, attach them to this process, and
  // add their message hooks to this window). Windows attaches IMEs while this
  // process creates a top-level window. On the other hand, to layout this
  // window correctly in the given parent window (RenderWidgetHostViewWin or
  // RenderWidgetHostViewAura), this window should be a child window of the
  // parent window. To satisfy both of the above conditions, this code once
  // creates a top-level window and change it to a child window of the parent
  // window (in the browser process).
    SetWindowLongPtr(windowed_handle_, GWL_STYLE,
                     WS_CHILD | WS_CLIPCHILDREN | WS_CLIPSIBLINGS);

  BOOL result = SetProp(windowed_handle_, kWebPluginDelegateProperty, this);
  DCHECK(result == TRUE) << "SetProp failed, last error = " << GetLastError();
  // Get the name and version of the plugin, create atoms and set them in a
  // window property. Use atoms so that other processes can access the name and
  // version of the plugin that this window is hosting.
  if (instance_ != NULL) {
    PluginLib* plugin_lib = instance()->plugin_lib();
    if (plugin_lib != NULL) {
      std::wstring plugin_name = plugin_lib->plugin_info().name;
      if (!plugin_name.empty()) {
        ATOM plugin_name_atom = GlobalAddAtomW(plugin_name.c_str());
        DCHECK_NE(0, plugin_name_atom);
        result = SetProp(windowed_handle_,
            kPluginNameAtomProperty,
            reinterpret_cast<HANDLE>(plugin_name_atom));
        DCHECK(result == TRUE) << "SetProp failed, last error = " <<
            GetLastError();
      }
      base::string16 plugin_version = plugin_lib->plugin_info().version;
      if (!plugin_version.empty()) {
        ATOM plugin_version_atom = GlobalAddAtomW(plugin_version.c_str());
        DCHECK_NE(0, plugin_version_atom);
        result = SetProp(windowed_handle_,
            kPluginVersionAtomProperty,
            reinterpret_cast<HANDLE>(plugin_version_atom));
        DCHECK(result == TRUE) << "SetProp failed, last error = " <<
            GetLastError();
      }
    }
  }

  // Calling SetWindowLongPtrA here makes the window proc ASCII, which is
  // required by at least the Shockwave Director plug-in.
  SetWindowLongPtrA(windowed_handle_,
                    GWLP_WNDPROC,
                    reinterpret_cast<LONG_PTR>(DefWindowProcA));

  return true;
}

void WebPluginDelegateImpl::WindowedDestroyWindow() {
  if (windowed_handle_ != NULL) {
    // Unsubclass the window.
    WNDPROC current_wnd_proc = reinterpret_cast<WNDPROC>(
        GetWindowLongPtr(windowed_handle_, GWLP_WNDPROC));
    if (current_wnd_proc == NativeWndProc) {
      SetWindowLongPtr(windowed_handle_,
                       GWLP_WNDPROC,
                       reinterpret_cast<LONG_PTR>(plugin_wnd_proc_));
    }

    plugin_->WillDestroyWindow(windowed_handle_);

    DestroyWindow(windowed_handle_);
    windowed_handle_ = 0;
  }
}

// Erase all messages in the queue destined for a particular window.
// When windows are closing, callers should use this function to clear
// the queue.
// static
void WebPluginDelegateImpl::ClearThrottleQueueForWindow(HWND window) {
  ThrottleQueue* throttle_queue = g_throttle_queue.Pointer();

  ThrottleQueue::iterator it;
  for (it = throttle_queue->begin(); it != throttle_queue->end(); ) {
    if (it->hwnd == window) {
      it = throttle_queue->erase(it);
    } else {
      it++;
    }
  }
}

// Delayed callback for processing throttled messages.
// Throttled messages are aggregated globally across all plugins.
// static
void WebPluginDelegateImpl::OnThrottleMessage() {
  // The current algorithm walks the list and processes the first
  // message it finds for each plugin.  It is important to service
  // all active plugins with each pass through the throttle, otherwise
  // we see video jankiness.  Copy the set to notify before notifying
  // since we may re-enter OnThrottleMessage from CallWindowProc!
  ThrottleQueue* throttle_queue = g_throttle_queue.Pointer();
  ThrottleQueue notify_queue;
  std::set<HWND> processed;

  ThrottleQueue::iterator it = throttle_queue->begin();
  while (it != throttle_queue->end()) {
    const MSG& msg = *it;
    if (processed.find(msg.hwnd) == processed.end()) {
      processed.insert(msg.hwnd);
      notify_queue.push_back(msg);
      it = throttle_queue->erase(it);
    } else {
      it++;
    }
  }

  // Due to re-entrancy, we must save our queue state now.  Otherwise, we may
  // self-post below, and *also* start up another delayed task when the first
  // entry is pushed onto the queue in ThrottleMessage().
  bool throttle_queue_was_empty = throttle_queue->empty();

  for (it = notify_queue.begin(); it != notify_queue.end(); ++it) {
    const MSG& msg = *it;
    WNDPROC proc = reinterpret_cast<WNDPROC>(msg.time);
    // It is possible that the window was closed after we queued
    // this message.  This is a rare event; just verify the window
    // is alive.  (see also bug 1259488)
    if (IsWindow(msg.hwnd))
      CallWindowProc(proc, msg.hwnd, msg.message, msg.wParam, msg.lParam);
  }

  if (!throttle_queue_was_empty) {
    base::MessageLoop::current()->PostDelayedTask(
        FROM_HERE,
        base::Bind(&WebPluginDelegateImpl::OnThrottleMessage),
        base::TimeDelta::FromMilliseconds(kFlashWMUSERMessageThrottleDelayMs));
  }
}

// Schedule a windows message for delivery later.
// static
void WebPluginDelegateImpl::ThrottleMessage(WNDPROC proc, HWND hwnd,
                                            UINT message, WPARAM wParam,
                                            LPARAM lParam) {
  MSG msg;
  msg.time = reinterpret_cast<DWORD>(proc);
  msg.hwnd = hwnd;
  msg.message = message;
  msg.wParam = wParam;
  msg.lParam = lParam;

  ThrottleQueue* throttle_queue = g_throttle_queue.Pointer();

  throttle_queue->push_back(msg);

  if (throttle_queue->size() == 1) {
    base::MessageLoop::current()->PostDelayedTask(
        FROM_HERE,
        base::Bind(&WebPluginDelegateImpl::OnThrottleMessage),
        base::TimeDelta::FromMilliseconds(kFlashWMUSERMessageThrottleDelayMs));
  }
}

// We go out of our way to find the hidden windows created by Flash for
// windowless plugins.  We throttle the rate at which they deliver messages
// so that they will not consume outrageous amounts of CPU.
// static
LRESULT CALLBACK WebPluginDelegateImpl::FlashWindowlessWndProc(
    HWND hwnd, UINT message, WPARAM wparam, LPARAM lparam) {
  std::map<HWND, WNDPROC>::iterator index =
      g_window_handle_proc_map.Get().find(hwnd);

  WNDPROC old_proc = (*index).second;
  DCHECK(old_proc);

  switch (message) {
    case WM_NCDESTROY: {
      WebPluginDelegateImpl::ClearThrottleQueueForWindow(hwnd);
      g_window_handle_proc_map.Get().erase(index);
      break;
    }
    // Flash may flood the message queue with WM_USER+1 message causing 100% CPU
    // usage.  See https://bugzilla.mozilla.org/show_bug.cgi?id=132759.  We
    // prevent this by throttling the messages.
    case WM_USER + 1: {
      WebPluginDelegateImpl::ThrottleMessage(old_proc, hwnd, message, wparam,
                                             lparam);
      return TRUE;
    }

    default: {
      break;
    }
  }
  return CallWindowProc(old_proc, hwnd, message, wparam, lparam);
}

LRESULT CALLBACK WebPluginDelegateImpl::DummyWindowProc(
    HWND hwnd, UINT message, WPARAM w_param, LPARAM l_param) {
  WebPluginDelegateImpl* delegate = reinterpret_cast<WebPluginDelegateImpl*>(
      GetProp(hwnd, kWebPluginDelegateProperty));
  CHECK(delegate);
  if (message == WM_WINDOWPOSCHANGING) {
    // We need to know when the dummy window is parented because windowless
    // plugins need the parent window for things like menus. There's no message
    // for a parent being changed, but a WM_WINDOWPOSCHANGING is sent so we
    // check every time we get it.
    // For non-aura builds, this never changes since RenderWidgetHostViewWin's
    // window is constant. For aura builds, this changes every time the tab gets
    // dragged to a new window.
    HWND parent = GetParent(hwnd);
    if (parent != delegate->dummy_window_parent_) {
      delegate->dummy_window_parent_ = parent;

      // Set the containing window handle as the instance window handle. This is
      // what Safari does. Not having a valid window handle causes subtle bugs
      // with plugins which retrieve the window handle and use it for things
      // like context menus. The window handle can be retrieved via
      // NPN_GetValue of NPNVnetscapeWindow.
      delegate->instance_->set_window_handle(parent);

      // The plugin caches the result of NPNVnetscapeWindow when we originally
      // called NPP_SetWindow, so force it to get the new value.
      delegate->WindowlessSetWindow();
    }
  } else if (message == WM_NCDESTROY) {
    RemoveProp(hwnd, kWebPluginDelegateProperty);
  }
  return CallWindowProc(
      delegate->old_dummy_window_proc_, hwnd, message, w_param, l_param);
}

// Callback for enumerating the Flash windows.
BOOL CALLBACK EnumFlashWindows(HWND window, LPARAM arg) {
  WNDPROC wnd_proc = reinterpret_cast<WNDPROC>(arg);
  TCHAR class_name[1024];
  if (!RealGetWindowClass(window, class_name,
                          sizeof(class_name)/sizeof(TCHAR))) {
    LOG(ERROR) << "RealGetWindowClass failure: " << GetLastError();
    return FALSE;
  }

  if (wcscmp(class_name, L"SWFlash_PlaceholderX"))
    return TRUE;

  WNDPROC current_wnd_proc = reinterpret_cast<WNDPROC>(
        GetWindowLongPtr(window, GWLP_WNDPROC));
  if (current_wnd_proc != wnd_proc) {
    WNDPROC old_flash_proc = reinterpret_cast<WNDPROC>(SetWindowLongPtr(
        window, GWLP_WNDPROC,
        reinterpret_cast<LONG_PTR>(wnd_proc)));
    DCHECK(old_flash_proc);
    g_window_handle_proc_map.Get()[window] = old_flash_proc;
  }

  return TRUE;
}

bool WebPluginDelegateImpl::CreateDummyWindowForActivation() {
  DCHECK(!dummy_window_for_activation_);

  dummy_window_for_activation_ = CreateWindowEx(
    0,
    L"Static",
    kDummyActivationWindowName,
    WS_CHILD,
    0,
    0,
    0,
    0,
    // We don't know the parent of the dummy window yet, so just set it to the
    // desktop and it'll get parented by the browser.
    GetDesktopWindow(),
    0,
    GetModuleHandle(NULL),
    0);

  if (dummy_window_for_activation_ == 0)
    return false;

  BOOL result = SetProp(dummy_window_for_activation_,
                        kWebPluginDelegateProperty, this);
  DCHECK(result == TRUE) << "SetProp failed, last error = " << GetLastError();
  old_dummy_window_proc_ = reinterpret_cast<WNDPROC>(SetWindowLongPtr(
      dummy_window_for_activation_, GWLP_WNDPROC,
      reinterpret_cast<LONG_PTR>(DummyWindowProc)));

  // Flash creates background windows which use excessive CPU in our
  // environment; we wrap these windows and throttle them so that they don't
  // get out of hand.
  if (!EnumThreadWindows(::GetCurrentThreadId(), EnumFlashWindows,
      reinterpret_cast<LPARAM>(
      &WebPluginDelegateImpl::FlashWindowlessWndProc))) {
    // Log that this happened.  Flash will still work; it just means the
    // throttle isn't installed (and Flash will use more CPU).
    NOTREACHED();
    LOG(ERROR) << "Failed to wrap all windowless Flash windows";
  }
  return true;
}

bool WebPluginDelegateImpl::WindowedReposition(
    const gfx::Rect& window_rect_in_dip,
    const gfx::Rect& clip_rect_in_dip) {
  if (!windowed_handle_) {
    NOTREACHED();
    return false;
  }

  gfx::Rect window_rect = gfx::win::DIPToScreenRect(window_rect_in_dip);
  gfx::Rect clip_rect = gfx::win::DIPToScreenRect(clip_rect_in_dip);
  if (window_rect_ == window_rect && clip_rect_ == clip_rect)
    return false;

  // We only set the plugin's size here.  Its position is moved elsewhere, which
  // allows the window moves/scrolling/clipping to be synchronized with the page
  // and other windows.
  // If the plugin window has no parent, then don't focus it because it isn't
  // being displayed anywhere. See:
  // http://code.google.com/p/chromium/issues/detail?id=32658
  if (window_rect.size() != window_rect_.size()) {
    UINT flags = SWP_NOMOVE | SWP_NOZORDER;
    if (!GetParent(windowed_handle_))
      flags |= SWP_NOACTIVATE;
    ::SetWindowPos(windowed_handle_,
                   NULL,
                   0,
                   0,
                   window_rect.width(),
                   window_rect.height(),
                   flags);
  }

  window_rect_ = window_rect;
  clip_rect_ = clip_rect;

  // Ensure that the entire window gets repainted.
  ::InvalidateRect(windowed_handle_, NULL, FALSE);

  return true;
}

void WebPluginDelegateImpl::WindowedSetWindow() {
  if (!instance_)
    return;

  if (!windowed_handle_) {
    NOTREACHED();
    return;
  }

  instance()->set_window_handle(windowed_handle_);

  DCHECK(!instance()->windowless());

  window_.clipRect.top = std::max(0, clip_rect_.y());
  window_.clipRect.left = std::max(0, clip_rect_.x());
  window_.clipRect.bottom = std::max(0, clip_rect_.y() + clip_rect_.height());
  window_.clipRect.right = std::max(0, clip_rect_.x() + clip_rect_.width());
  window_.height = window_rect_.height();
  window_.width = window_rect_.width();
  window_.x = 0;
  window_.y = 0;

  window_.window = windowed_handle_;
  window_.type = NPWindowTypeWindow;

  // Reset this flag before entering the instance in case of side-effects.
  windowed_did_set_window_ = true;

  NPError err = instance()->NPP_SetWindow(&window_);
  if (quirks_ & PLUGIN_QUIRK_SETWINDOW_TWICE)
    instance()->NPP_SetWindow(&window_);

  WNDPROC current_wnd_proc = reinterpret_cast<WNDPROC>(
        GetWindowLongPtr(windowed_handle_, GWLP_WNDPROC));
  if (current_wnd_proc != NativeWndProc) {
    plugin_wnd_proc_ = reinterpret_cast<WNDPROC>(
        SetWindowLongPtr(windowed_handle_,
                         GWLP_WNDPROC,
                         reinterpret_cast<LONG_PTR>(NativeWndProc)));
  }
}

ATOM WebPluginDelegateImpl::RegisterNativeWindowClass() {
  static bool have_registered_window_class = false;
  if (have_registered_window_class == true)
    return true;

  have_registered_window_class = true;

  WNDCLASSEX wcex;
  wcex.cbSize         = sizeof(WNDCLASSEX);
  wcex.style          = CS_DBLCLKS;
  wcex.lpfnWndProc    = WrapperWindowProc;
  wcex.cbClsExtra     = 0;
  wcex.cbWndExtra     = 0;
  wcex.hInstance      = GetModuleHandle(NULL);
  wcex.hIcon          = 0;
  wcex.hCursor        = 0;
  // Some plugins like windows media player 11 create child windows parented
  // by our plugin window, where the media content is rendered. These plugins
  // dont implement WM_ERASEBKGND, which causes painting issues, when the
  // window where the media is rendered is moved around. DefWindowProc does
  // implement WM_ERASEBKGND correctly if we have a valid background brush.
  wcex.hbrBackground  = reinterpret_cast<HBRUSH>(COLOR_WINDOW+1);
  wcex.lpszMenuName   = 0;
  wcex.lpszClassName  = kNativeWindowClassName;
  wcex.hIconSm        = 0;

  return RegisterClassEx(&wcex);
}

LRESULT CALLBACK WebPluginDelegateImpl::WrapperWindowProc(
    HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam) {
  // This is another workaround for Issue 2673 in chromium "Flash: IME not
  // available". Somehow, the CallWindowProc() function does not dispatch
  // window messages when its first parameter is a handle representing the
  // DefWindowProc() function. To avoid this problem, this code creates a
  // wrapper function which just encapsulates the DefWindowProc() function
  // and set it as the window procedure of a windowed plug-in.
  return DefWindowProc(hWnd, message, wParam, lParam);
}

// Returns true if the message passed in corresponds to a user gesture.
static bool IsUserGestureMessage(unsigned int message) {
  switch (message) {
    case WM_LBUTTONDOWN:
    case WM_LBUTTONUP:
    case WM_RBUTTONDOWN:
    case WM_RBUTTONUP:
    case WM_MBUTTONDOWN:
    case WM_MBUTTONUP:
    case WM_KEYDOWN:
    case WM_KEYUP:
      return true;

    default:
      break;
  }

  return false;
}

LRESULT CALLBACK WebPluginDelegateImpl::NativeWndProc(
    HWND hwnd, UINT message, WPARAM wparam, LPARAM lparam) {
  WebPluginDelegateImpl* delegate = reinterpret_cast<WebPluginDelegateImpl*>(
      GetProp(hwnd, kWebPluginDelegateProperty));
  if (!delegate) {
    NOTREACHED();
    return 0;
  }

  if (message == delegate->last_message_ &&
      delegate->GetQuirks() & PLUGIN_QUIRK_DONT_CALL_WND_PROC_RECURSIVELY &&
      delegate->is_calling_wndproc) {
    // Real may go into a state where it recursively dispatches the same event
    // when subclassed.  See https://bugzilla.mozilla.org/show_bug.cgi?id=192914
    // We only do the recursive check for Real because it's possible and valid
    // for a plugin to synchronously dispatch a message to itself such that it
    // looks like it's in recursion.
    return TRUE;
  }

  // Flash may flood the message queue with WM_USER+1 message causing 100% CPU
  // usage.  See https://bugzilla.mozilla.org/show_bug.cgi?id=132759.  We
  // prevent this by throttling the messages.
  if (message == WM_USER + 1 &&
      delegate->GetQuirks() & PLUGIN_QUIRK_THROTTLE_WM_USER_PLUS_ONE) {
    WebPluginDelegateImpl::ThrottleMessage(delegate->plugin_wnd_proc_, hwnd,
                                           message, wparam, lparam);
    return FALSE;
  }

  LRESULT result;
  uint32 old_message = delegate->last_message_;
  delegate->last_message_ = message;

  static UINT custom_msg = RegisterWindowMessage(kPaintMessageName);
  if (message == custom_msg) {
    // Get the invalid rect which is in screen coordinates and convert to
    // window coordinates.
    gfx::Rect invalid_rect;
    invalid_rect.set_x(static_cast<short>(LOWORD(wparam)));
    invalid_rect.set_y(static_cast<short>(HIWORD(wparam)));
    invalid_rect.set_width(static_cast<short>(LOWORD(lparam)));
    invalid_rect.set_height(static_cast<short>(HIWORD(lparam)));

    RECT window_rect;
    GetWindowRect(hwnd, &window_rect);
    invalid_rect.Offset(-window_rect.left, -window_rect.top);

    // The plugin window might have non-client area.   If we don't pass in
    // RDW_FRAME then the children don't receive WM_NCPAINT messages while
    // scrolling, which causes painting problems (http://b/issue?id=923945).
    uint32 flags = RDW_INVALIDATE | RDW_ALLCHILDREN | RDW_FRAME;

    // If a plugin (like Google Earth or Java) has child windows that are hosted
    // in a different process, then RedrawWindow with UPDATENOW will
    // synchronously wait for this call to complete.  Some messages are pumped
    // but not others, which could lead to a deadlock.  So avoid reentrancy by
    // only synchronously calling RedrawWindow once at a time.
    if (old_message != custom_msg)
      flags |= RDW_UPDATENOW;
    RECT rect = invalid_rect.ToRECT();
    RedrawWindow(hwnd, &rect, NULL, flags);
    result = FALSE;
  } else {
    delegate->is_calling_wndproc = true;

    if (!delegate->user_gesture_message_posted_ &&
        IsUserGestureMessage(message)) {
      delegate->user_gesture_message_posted_ = true;

      delegate->instance()->PushPopupsEnabledState(true);

      base::MessageLoop::current()->PostDelayedTask(
          FROM_HERE,
          base::Bind(&WebPluginDelegateImpl::OnUserGestureEnd,
                     delegate->user_gesture_msg_factory_.GetWeakPtr()),
          base::TimeDelta::FromMilliseconds(kWindowedPluginPopupTimerMs));
    }

    HandleCaptureForMessage(hwnd, message);

    // Maintain a local/global stack for the g_current_plugin_instance variable
    // as this may be a nested invocation.
    WebPluginDelegateImpl* last_plugin_instance = g_current_plugin_instance;

    g_current_plugin_instance = delegate;

    result = CallWindowProc(
        delegate->plugin_wnd_proc_, hwnd, message, wparam, lparam);

    // The plugin instance may have been destroyed in the CallWindowProc call
    // above. This will also destroy the plugin window. Before attempting to
    // access the WebPluginDelegateImpl instance we validate if the window is
    // still valid.
    if (::IsWindow(hwnd))
      delegate->is_calling_wndproc = false;

    g_current_plugin_instance = last_plugin_instance;

    if (message == WM_NCDESTROY) {
      RemoveProp(hwnd, kWebPluginDelegateProperty);
      ATOM plugin_name_atom = reinterpret_cast<ATOM>(
          RemoveProp(hwnd, kPluginNameAtomProperty));
      if (plugin_name_atom != 0)
        GlobalDeleteAtom(plugin_name_atom);
      ATOM plugin_version_atom = reinterpret_cast<ATOM>(
          RemoveProp(hwnd, kPluginVersionAtomProperty));
      if (plugin_version_atom != 0)
        GlobalDeleteAtom(plugin_version_atom);
      ClearThrottleQueueForWindow(hwnd);
    }
  }
  if (::IsWindow(hwnd))
    delegate->last_message_ = old_message;
  return result;
}

void WebPluginDelegateImpl::WindowlessUpdateGeometry(
    const gfx::Rect& window_rect,
    const gfx::Rect& clip_rect) {
  bool window_rect_changed = (window_rect_ != window_rect);
  // Only resend to the instance if the geometry has changed.
  if (!window_rect_changed && clip_rect == clip_rect_)
    return;

  clip_rect_ = clip_rect;
  window_rect_ = window_rect;

  WindowlessSetWindow();

  if (window_rect_changed) {
    WINDOWPOS win_pos = {0};
    win_pos.x = window_rect_.x();
    win_pos.y = window_rect_.y();
    win_pos.cx = window_rect_.width();
    win_pos.cy = window_rect_.height();

    NPEvent pos_changed_event;
    pos_changed_event.event = WM_WINDOWPOSCHANGED;
    pos_changed_event.wParam = 0;
    pos_changed_event.lParam = PtrToUlong(&win_pos);

    instance()->NPP_HandleEvent(&pos_changed_event);
  }
}

void WebPluginDelegateImpl::WindowlessPaint(HDC hdc,
                                            const gfx::Rect& damage_rect) {
  DCHECK(hdc);

  RECT damage_rect_win;
  damage_rect_win.left   = damage_rect.x();  // + window_rect_.x();
  damage_rect_win.top    = damage_rect.y();  // + window_rect_.y();
  damage_rect_win.right  = damage_rect_win.left + damage_rect.width();
  damage_rect_win.bottom = damage_rect_win.top + damage_rect.height();

  // Save away the old HDC as this could be a nested invocation.
  void* old_dc = window_.window;
  window_.window = hdc;

  NPEvent paint_event;
  paint_event.event = WM_PAINT;
  // NOTE: NPAPI is not 64bit safe.  It puts pointers into 32bit values.
  paint_event.wParam = PtrToUlong(hdc);
  paint_event.lParam = PtrToUlong(&damage_rect_win);
  base::StatsRate plugin_paint("Plugin.Paint");
  base::StatsScope<base::StatsRate> scope(plugin_paint);
  instance()->NPP_HandleEvent(&paint_event);
  window_.window = old_dc;
}

void WebPluginDelegateImpl::WindowlessSetWindow() {
  if (!instance())
    return;

  if (window_rect_.IsEmpty())  // wait for geometry to be set.
    return;

  DCHECK(instance()->windowless());

  window_.clipRect.top = clip_rect_.y();
  window_.clipRect.left = clip_rect_.x();
  window_.clipRect.bottom = clip_rect_.y() + clip_rect_.height();
  window_.clipRect.right = clip_rect_.x() + clip_rect_.width();
  window_.height = window_rect_.height();
  window_.width = window_rect_.width();
  window_.x = window_rect_.x();
  window_.y = window_rect_.y();
  window_.type = NPWindowTypeDrawable;
  DrawableContextEnforcer enforcer(&window_);

  NPError err = instance()->NPP_SetWindow(&window_);
  DCHECK(err == NPERR_NO_ERROR);
}

bool WebPluginDelegateImpl::PlatformSetPluginHasFocus(bool focused) {
  DCHECK(instance()->windowless());

  NPEvent focus_event;
  focus_event.event = focused ? WM_SETFOCUS : WM_KILLFOCUS;
  focus_event.wParam = 0;
  focus_event.lParam = 0;

  instance()->NPP_HandleEvent(&focus_event);
  return true;
}

static bool NPEventFromWebMouseEvent(const WebMouseEvent& event,
                                     NPEvent* np_event) {
  np_event->lParam = static_cast<uint32>(MAKELPARAM(event.windowX,
                                                   event.windowY));
  np_event->wParam = 0;

  if (event.modifiers & WebInputEvent::ControlKey)
    np_event->wParam |= MK_CONTROL;
  if (event.modifiers & WebInputEvent::ShiftKey)
    np_event->wParam |= MK_SHIFT;
  if (event.modifiers & WebInputEvent::LeftButtonDown)
    np_event->wParam |= MK_LBUTTON;
  if (event.modifiers & WebInputEvent::MiddleButtonDown)
    np_event->wParam |= MK_MBUTTON;
  if (event.modifiers & WebInputEvent::RightButtonDown)
    np_event->wParam |= MK_RBUTTON;

  switch (event.type) {
    case WebInputEvent::MouseMove:
    case WebInputEvent::MouseLeave:
    case WebInputEvent::MouseEnter:
      np_event->event = WM_MOUSEMOVE;
      return true;
    case WebInputEvent::MouseDown:
      switch (event.button) {
        case WebMouseEvent::ButtonLeft:
          np_event->event = WM_LBUTTONDOWN;
          break;
        case WebMouseEvent::ButtonMiddle:
          np_event->event = WM_MBUTTONDOWN;
          break;
        case WebMouseEvent::ButtonRight:
          np_event->event = WM_RBUTTONDOWN;
          break;
      }
      return true;
    case WebInputEvent::MouseUp:
      switch (event.button) {
        case WebMouseEvent::ButtonLeft:
          np_event->event = WM_LBUTTONUP;
          break;
        case WebMouseEvent::ButtonMiddle:
          np_event->event = WM_MBUTTONUP;
          break;
        case WebMouseEvent::ButtonRight:
          np_event->event = WM_RBUTTONUP;
          break;
      }
      return true;
    default:
      NOTREACHED();
      return false;
  }
}

static bool NPEventFromWebKeyboardEvent(const WebKeyboardEvent& event,
                                        NPEvent* np_event) {
  np_event->wParam = event.windowsKeyCode;

  switch (event.type) {
    case WebInputEvent::KeyDown:
      np_event->event = WM_KEYDOWN;
      np_event->lParam = 0;
      return true;
    case WebInputEvent::Char:
      np_event->event = WM_CHAR;
      np_event->lParam = 0;
      return true;
    case WebInputEvent::KeyUp:
      np_event->event = WM_KEYUP;
      np_event->lParam = 0x8000;
      return true;
    default:
      NOTREACHED();
      return false;
  }
}

static bool NPEventFromWebInputEvent(const WebInputEvent& event,
                                     NPEvent* np_event) {
  switch (event.type) {
    case WebInputEvent::MouseMove:
    case WebInputEvent::MouseLeave:
    case WebInputEvent::MouseEnter:
    case WebInputEvent::MouseDown:
    case WebInputEvent::MouseUp:
      if (event.size < sizeof(WebMouseEvent)) {
        NOTREACHED();
        return false;
      }
      return NPEventFromWebMouseEvent(
          *static_cast<const WebMouseEvent*>(&event), np_event);
    case WebInputEvent::KeyDown:
    case WebInputEvent::Char:
    case WebInputEvent::KeyUp:
      if (event.size < sizeof(WebKeyboardEvent)) {
        NOTREACHED();
        return false;
      }
      return NPEventFromWebKeyboardEvent(
          *static_cast<const WebKeyboardEvent*>(&event), np_event);
    default:
      return false;
  }
}

bool WebPluginDelegateImpl::PlatformHandleInputEvent(
    const WebInputEvent& event, WebCursor::CursorInfo* cursor_info) {
  DCHECK(cursor_info != NULL);

  NPEvent np_event;
  if (!NPEventFromWebInputEvent(event, &np_event)) {
    return false;
  }

  // Allow this plug-in to access this IME emulator through IMM32 API while the
  // plug-in is processing this event.
  if (GetQuirks() & PLUGIN_QUIRK_EMULATE_IME) {
    if (!plugin_ime_)
      plugin_ime_.reset(new WebPluginIMEWin);
  }
  WebPluginIMEWin::ScopedLock lock(
      event.isKeyboardEventType(event.type) ? plugin_ime_.get() : NULL);

  HWND last_focus_window = NULL;

  if (ShouldTrackEventForModalLoops(&np_event)) {
    // A windowless plugin can enter a modal loop in a NPP_HandleEvent call.
    // For e.g. Flash puts up a context menu when we right click on the
    // windowless plugin area. We detect this by setting up a message filter
    // hook pror to calling NPP_HandleEvent on the plugin and unhook on
    // return from NPP_HandleEvent. If the plugin does enter a modal loop
    // in that context we unhook on receiving the first notification in
    // the message filter hook.
    handle_event_message_filter_hook_ =
        SetWindowsHookEx(WH_MSGFILTER, HandleEventMessageFilterHook, NULL,
                         GetCurrentThreadId());
    // To ensure that the plugin receives keyboard events we set focus to the
    // dummy window.
    // TODO(iyengar) We need a framework in the renderer to identify which
    // windowless plugin is under the mouse and to handle this. This would
    // also require some changes in RenderWidgetHost to detect this in the
    // WM_MOUSEACTIVATE handler and inform the renderer accordingly.
    bool valid = GetParent(dummy_window_for_activation_) != GetDesktopWindow();
    if (valid) {
      last_focus_window = ::SetFocus(dummy_window_for_activation_);
    } else {
      NOTREACHED() << "Dummy window not parented";
    }
  }

  bool old_task_reentrancy_state =
      base::MessageLoop::current()->NestableTasksAllowed();

  // Maintain a local/global stack for the g_current_plugin_instance variable
  // as this may be a nested invocation.
  WebPluginDelegateImpl* last_plugin_instance = g_current_plugin_instance;

  g_current_plugin_instance = this;

  handle_event_depth_++;

  bool popups_enabled = false;

  if (IsUserGestureMessage(np_event.event)) {
    instance()->PushPopupsEnabledState(true);
    popups_enabled = true;
  }

  bool ret = instance()->NPP_HandleEvent(&np_event) != 0;

  if (popups_enabled) {
    instance()->PopPopupsEnabledState();
  }

  // Flash and SilverLight always return false, even when they swallow the
  // event.  Flash does this because it passes the event to its window proc,
  // which is supposed to return 0 if an event was handled.  There are few
  // exceptions, such as IME, where it sometimes returns true.
  ret = true;

  if (np_event.event == WM_MOUSEMOVE) {
    current_windowless_cursor_.InitFromExternalCursor(GetCursor());
    // Snag a reference to the current cursor ASAP in case the plugin modified
    // it. There is a nasty race condition here with the multiprocess browser
    // as someone might be setting the cursor in the main process as well.
    current_windowless_cursor_.GetCursorInfo(cursor_info);
  }

  handle_event_depth_--;

  g_current_plugin_instance = last_plugin_instance;

  // We could have multiple NPP_HandleEvent calls nested together in case
  // the plugin enters a modal loop. Reset the pump messages event when
  // the outermost NPP_HandleEvent call unwinds.
  if (handle_event_depth_ == 0) {
    ResetEvent(handle_event_pump_messages_event_);
  }

  // If we didn't enter a modal loop, need to unhook the filter.
  if (handle_event_message_filter_hook_) {
    UnhookWindowsHookEx(handle_event_message_filter_hook_);
    handle_event_message_filter_hook_ = NULL;
  }

  if (::IsWindow(last_focus_window)) {
    // Restore the nestable tasks allowed state in the message loop and reset
    // the os modal loop state as the plugin returned from the TrackPopupMenu
    // API call.
    base::MessageLoop::current()->SetNestableTasksAllowed(
        old_task_reentrancy_state);
    base::MessageLoop::current()->set_os_modal_loop(false);
    // The Flash plugin at times sets focus to its hidden top level window
    // with class name SWFlash_PlaceholderX. This causes the chrome browser
    // window to receive a WM_ACTIVATEAPP message as a top level window from
    // another thread is now active. We end up in a state where the chrome
    // browser window is not active even though the user clicked on it.
    // Our workaround for this is to send over a raw
    // WM_LBUTTONDOWN/WM_LBUTTONUP combination to the last focus window, which
    // does the trick.
    if (dummy_window_for_activation_ != ::GetFocus()) {
      INPUT input_info = {0};
      input_info.type = INPUT_MOUSE;
      input_info.mi.dwFlags = MOUSEEVENTF_LEFTDOWN;
      ::SendInput(1, &input_info, sizeof(INPUT));

      input_info.type = INPUT_MOUSE;
      input_info.mi.dwFlags = MOUSEEVENTF_LEFTUP;
      ::SendInput(1, &input_info, sizeof(INPUT));
    } else {
      ::SetFocus(last_focus_window);
    }
  }
  return ret;
}


void WebPluginDelegateImpl::OnModalLoopEntered() {
  DCHECK(handle_event_pump_messages_event_ != NULL);
  SetEvent(handle_event_pump_messages_event_);

  base::MessageLoop::current()->SetNestableTasksAllowed(true);
  base::MessageLoop::current()->set_os_modal_loop(true);

  UnhookWindowsHookEx(handle_event_message_filter_hook_);
  handle_event_message_filter_hook_ = NULL;
}

bool WebPluginDelegateImpl::ShouldTrackEventForModalLoops(NPEvent* event) {
  if (event->event == WM_RBUTTONDOWN)
    return true;
  return false;
}

void WebPluginDelegateImpl::OnUserGestureEnd() {
  user_gesture_message_posted_ = false;
  instance()->PopPopupsEnabledState();
}

BOOL WINAPI WebPluginDelegateImpl::TrackPopupMenuPatch(
    HMENU menu, unsigned int flags, int x, int y, int reserved,
    HWND window, const RECT* rect) {

  if (g_current_plugin_instance) {
    unsigned long window_process_id = 0;
    unsigned long window_thread_id =
        GetWindowThreadProcessId(window, &window_process_id);
    // TrackPopupMenu fails if the window passed in belongs to a different
    // thread.
    if (::GetCurrentThreadId() != window_thread_id) {
      bool valid =
          GetParent(g_current_plugin_instance->dummy_window_for_activation_) !=
              GetDesktopWindow();
      if (valid) {
        window = g_current_plugin_instance->dummy_window_for_activation_;
      } else {
        NOTREACHED() << "Dummy window not parented";
      }
    }
  }

  BOOL result = TrackPopupMenu(menu, flags, x, y, reserved, window, rect);
  return result;
}

HCURSOR WINAPI WebPluginDelegateImpl::SetCursorPatch(HCURSOR cursor) {
  // The windowless flash plugin periodically calls SetCursor in a wndproc
  // instantiated on the plugin thread. This causes annoying cursor flicker
  // when the mouse is moved on a foreground tab, with a windowless plugin
  // instance in a background tab. We just ignore the call here.
  if (!g_current_plugin_instance) {
    HCURSOR current_cursor = GetCursor();
    if (current_cursor != cursor) {
      ::SetCursor(cursor);
    }
    return current_cursor;
  }
  return ::SetCursor(cursor);
}

LONG WINAPI WebPluginDelegateImpl::RegEnumKeyExWPatch(
    HKEY key, DWORD index, LPWSTR name, LPDWORD name_size, LPDWORD reserved,
    LPWSTR class_name, LPDWORD class_size, PFILETIME last_write_time) {
  DWORD orig_size = *name_size;
  LONG rv = RegEnumKeyExW(key, index, name, name_size, reserved, class_name,
                          class_size, last_write_time);
  if (rv == ERROR_SUCCESS &&
      GetKeyPath(key).find(L"Microsoft\\MediaPlayer\\ShimInclusionList") !=
          std::wstring::npos) {
    static const wchar_t kChromeExeName[] = L"chrome.exe";
    wcsncpy_s(name, orig_size, kChromeExeName, arraysize(kChromeExeName));
    *name_size =
        std::min(orig_size, static_cast<DWORD>(arraysize(kChromeExeName)));
  }

  return rv;
}

void WebPluginDelegateImpl::ImeCompositionUpdated(
    const base::string16& text,
    const std::vector<int>& clauses,
    const std::vector<int>& target,
    int cursor_position) {
  if (!plugin_ime_)
    plugin_ime_.reset(new WebPluginIMEWin);

  plugin_ime_->CompositionUpdated(text, clauses, target, cursor_position);
  plugin_ime_->SendEvents(instance());
}

void WebPluginDelegateImpl::ImeCompositionCompleted(
    const base::string16& text) {
  if (!plugin_ime_)
    plugin_ime_.reset(new WebPluginIMEWin);
  plugin_ime_->CompositionCompleted(text);
  plugin_ime_->SendEvents(instance());
}

bool WebPluginDelegateImpl::GetIMEStatus(int* input_type,
                                         gfx::Rect* caret_rect) {
  if (!plugin_ime_)
    return false;
  return plugin_ime_->GetStatus(input_type, caret_rect);
}

// static
FARPROC WINAPI WebPluginDelegateImpl::GetProcAddressPatch(HMODULE module,
                                                          LPCSTR name) {
  FARPROC imm_function = WebPluginIMEWin::GetProcAddress(name);
  if (imm_function)
    return imm_function;
  return ::GetProcAddress(module, name);
}

HWND WINAPI WebPluginDelegateImpl::WindowFromPointPatch(POINT point) {
  HWND window = WindowFromPoint(point);
  if (::ScreenToClient(window, &point)) {
    HWND child = ChildWindowFromPoint(window, point);
    if (::IsWindow(child) &&
        ::GetProp(child, content::kPluginDummyParentProperty))
      return child;
  }
  return window;
}

void WebPluginDelegateImpl::HandleCaptureForMessage(HWND window,
                                                    UINT message) {
  if (gfx::GetClassName(window) != base::string16(kNativeWindowClassName))
    return;

  switch (message) {
    case WM_LBUTTONDOWN:
    case WM_MBUTTONDOWN:
    case WM_RBUTTONDOWN:
      ::SetCapture(window);
      // As per documentation the WM_PARENTNOTIFY message is sent to the parent
      // window chain if mouse input is received by the child window. However
      // the parent receives the WM_PARENTNOTIFY message only if we doubleclick
      // on the window. We send the WM_PARENTNOTIFY message for mouse input
      // messages to the parent to indicate that user action is expected.
      ::SendMessage(::GetParent(window), WM_PARENTNOTIFY, message, 0);
      break;

    case WM_LBUTTONUP:
    case WM_MBUTTONUP:
    case WM_RBUTTONUP:
      ::ReleaseCapture();
      break;

    default:
      break;
  }
}

}  // namespace content