chrome/browser/ui/views/tabs/tab_drag

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This source file includes following definitions.
SetWindowPositionManaged
IsDockedOrSnapped
DoesRectContainVerticalPointExpanded
OffsetX
OnWidgetVisibilityChanged
pinned
weak_factory_
Init
IsAttachedTo
IsActive
SetMoveBehavior
EndDrag
InitTabDragData
OpenURLFromTab
NavigationStateChanged
AddNewContents
ShouldSuppressDialogs
GetJavaScriptDialogManager
RequestMediaAccessPermission
Observe
WillProcessEvent
DidProcessEvent
OnWidgetBoundsChanged
TabStripEmpty
InitWindowCreatePoint
GetWindowCreatePoint
SaveFocus
RestoreFocus
CanStartDrag
ContinueDragging
DragBrowserToNewTabStrip
DragActiveTabStacked
MoveAttachedToNextStackedIndex
MoveAttachedToPreviousStackedIndex
MoveAttached
StartMoveStackedTimerIfNecessary
GetDetachPosition
GetTargetTabStripForPoint
GetTabStripForWindow
DoesTabStripContain
Attach
Detach
DetachIntoNewBrowserAndRunMoveLoop
RunMoveLoop
GetInsertionIndexFrom
GetInsertionIndexForDraggedBounds
ShouldDragToNextStackedTab
ShouldDragToPreviousStackedTab
GetInsertionIndexForDraggedBoundsStacked
GetDraggedViewTabStripBounds
GetAttachedDragPoint
GetTabsMatchingDraggedContents
CalculateBoundsForDraggedTabs
EndDragImpl
RevertDrag
ResetSelection
RestoreInitialSelection
RevertDragAt
CompleteDrag
MaximizeAttachedWindow
ResetDelegates
GetViewScreenBounds
CleanUpHiddenFrame
BringWindowUnderPointToFront
GetModel
GetAttachedBrowserWidget
AreTabsConsecutive
CalculateDraggedBrowserBounds
AdjustBrowserAndTabBoundsForDrag
CreateBrowserForDrag
GetCursorScreenPoint
GetWindowOffset
GetLocalProcessWindow
// 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 "chrome/browser/ui/views/tabs/tab_drag_controller.h"

#include <math.h>
#include <set>

#include "base/auto_reset.h"
#include "base/callback.h"
#include "base/command_line.h"
#include "base/i18n/rtl.h"
#include "chrome/browser/chrome_notification_types.h"
#include "chrome/browser/profiles/profile.h"
#include "chrome/browser/ui/app_modal_dialogs/javascript_dialog_manager.h"
#include "chrome/browser/ui/browser_list.h"
#include "chrome/browser/ui/browser_window.h"
#include "chrome/browser/ui/media_utils.h"
#include "chrome/browser/ui/tabs/tab_strip_model.h"
#include "chrome/browser/ui/tabs/tab_strip_model_delegate.h"
#include "chrome/browser/ui/views/frame/browser_view.h"
#include "chrome/browser/ui/views/tabs/browser_tab_strip_controller.h"
#include "chrome/browser/ui/views/tabs/stacked_tab_strip_layout.h"
#include "chrome/browser/ui/views/tabs/tab.h"
#include "chrome/browser/ui/views/tabs/tab_strip.h"
#include "chrome/browser/ui/views/tabs/window_finder.h"
#include "chrome/common/chrome_switches.h"
#include "content/public/browser/invalidate_type.h"
#include "content/public/browser/notification_details.h"
#include "content/public/browser/notification_service.h"
#include "content/public/browser/notification_source.h"
#include "content/public/browser/notification_types.h"
#include "content/public/browser/user_metrics.h"
#include "content/public/browser/web_contents.h"
#include "content/public/browser/web_contents_view.h"
#include "extensions/browser/extension_function_dispatcher.h"
#include "ui/base/resource/resource_bundle.h"
#include "ui/events/event_constants.h"
#include "ui/events/event_utils.h"
#include "ui/gfx/geometry/point_conversions.h"
#include "ui/gfx/screen.h"
#include "ui/views/focus/view_storage.h"
#include "ui/views/widget/root_view.h"
#include "ui/views/widget/widget.h"

#if defined(USE_ASH)
#include "ash/accelerators/accelerator_commands.h"
#include "ash/wm/coordinate_conversion.h"
#include "ash/wm/window_state.h"
#include "ui/aura/env.h"
#include "ui/aura/window.h"
#include "ui/aura/window_event_dispatcher.h"
#include "ui/events/gestures/gesture_recognizer.h"
#endif

#if defined(OS_WIN)
#include "ui/aura/window.h"
#include "ui/events/gestures/gesture_recognizer.h"
#endif

using base::UserMetricsAction;
using content::OpenURLParams;
using content::WebContents;

// If non-null there is a drag underway.
static TabDragController* instance_ = NULL;

namespace {

// Delay, in ms, during dragging before we bring a window to front.
const int kBringToFrontDelay = 750;

// Initial delay before moving tabs when the dragged tab is close to the edge of
// the stacked tabs.
const int kMoveAttachedInitialDelay = 600;

// Delay for moving tabs after the initial delay has passed.
const int kMoveAttachedSubsequentDelay = 300;

const int kHorizontalMoveThreshold = 16;  // Pixels.

// Distance from the next/previous stacked before before we consider the tab
// close enough to trigger moving.
const int kStackedDistance = 36;

void SetWindowPositionManaged(gfx::NativeWindow window, bool value) {
#if defined(USE_ASH)
  ash::wm::GetWindowState(window)->set_window_position_managed(value);
#endif
}

// Returns true if |tab_strip| browser window is docked.
bool IsDockedOrSnapped(const TabStrip* tab_strip) {
#if defined(USE_ASH)
  DCHECK(tab_strip);
  ash::wm::WindowState* window_state =
      ash::wm::GetWindowState(tab_strip->GetWidget()->GetNativeWindow());
  return window_state->IsDocked() || window_state->IsSnapped();
#else
  return false;
#endif
}

// Returns true if |bounds| contains the y-coordinate |y|. The y-coordinate
// of |bounds| is adjusted by |vertical_adjustment|.
bool DoesRectContainVerticalPointExpanded(
    const gfx::Rect& bounds,
    int vertical_adjustment,
    int y) {
  int upper_threshold = bounds.bottom() + vertical_adjustment;
  int lower_threshold = bounds.y() - vertical_adjustment;
  return y >= lower_threshold && y <= upper_threshold;
}

// Adds |x_offset| to all the rectangles in |rects|.
void OffsetX(int x_offset, std::vector<gfx::Rect>* rects) {
  if (x_offset == 0)
    return;

  for (size_t i = 0; i < rects->size(); ++i)
    (*rects)[i].set_x((*rects)[i].x() + x_offset);
}

// WidgetObserver implementation that resets the window position managed
// property on Show.
// We're forced to do this here since BrowserFrameAsh resets the 'window
// position managed' property during a show and we need the property set to
// false before WorkspaceLayoutManager sees the visibility change.
class WindowPositionManagedUpdater : public views::WidgetObserver {
 public:
  virtual void OnWidgetVisibilityChanged(views::Widget* widget,
                                         bool visible) OVERRIDE {
    SetWindowPositionManaged(widget->GetNativeView(), false);
  }
};

}  // namespace

TabDragController::TabDragData::TabDragData()
    : contents(NULL),
      original_delegate(NULL),
      source_model_index(-1),
      attached_tab(NULL),
      pinned(false) {
}

TabDragController::TabDragData::~TabDragData() {
}

///////////////////////////////////////////////////////////////////////////////
// TabDragController, public:

// static
const int TabDragController::kTouchVerticalDetachMagnetism = 50;

// static
const int TabDragController::kVerticalDetachMagnetism = 15;

TabDragController::TabDragController()
    : detach_into_browser_(true),
      event_source_(EVENT_SOURCE_MOUSE),
      source_tabstrip_(NULL),
      attached_tabstrip_(NULL),
      screen_(NULL),
      host_desktop_type_(chrome::HOST_DESKTOP_TYPE_NATIVE),
      use_aura_capture_policy_(false),
      offset_to_width_ratio_(0),
      old_focused_view_id_(
          views::ViewStorage::GetInstance()->CreateStorageID()),
      last_move_screen_loc_(0),
      started_drag_(false),
      active_(true),
      source_tab_index_(std::numeric_limits<size_t>::max()),
      initial_move_(true),
      detach_behavior_(DETACHABLE),
      move_behavior_(REORDER),
      mouse_move_direction_(0),
      is_dragging_window_(false),
      is_dragging_new_browser_(false),
      was_source_maximized_(false),
      was_source_fullscreen_(false),
      did_restore_window_(false),
      end_run_loop_behavior_(END_RUN_LOOP_STOP_DRAGGING),
      waiting_for_run_loop_to_exit_(false),
      tab_strip_to_attach_to_after_exit_(NULL),
      move_loop_widget_(NULL),
      is_mutating_(false),
      attach_x_(-1),
      attach_index_(-1),
      weak_factory_(this) {
  instance_ = this;
}

TabDragController::~TabDragController() {
  views::ViewStorage::GetInstance()->RemoveView(old_focused_view_id_);

  if (instance_ == this)
    instance_ = NULL;

  if (move_loop_widget_) {
    move_loop_widget_->RemoveObserver(this);
    SetWindowPositionManaged(move_loop_widget_->GetNativeView(), true);
  }

  if (source_tabstrip_ && detach_into_browser_)
    GetModel(source_tabstrip_)->RemoveObserver(this);

  base::MessageLoopForUI::current()->RemoveObserver(this);

  // Reset the delegate of the dragged WebContents. This ends up doing nothing
  // if the drag was completed.
  if (!detach_into_browser_)
    ResetDelegates();

  if (event_source_ == EVENT_SOURCE_TOUCH) {
    TabStrip* capture_tabstrip = (attached_tabstrip_ && detach_into_browser_) ?
        attached_tabstrip_ : source_tabstrip_;
    capture_tabstrip->GetWidget()->ReleaseCapture();
  }
}

void TabDragController::Init(
    TabStrip* source_tabstrip,
    Tab* source_tab,
    const std::vector<Tab*>& tabs,
    const gfx::Point& mouse_offset,
    int source_tab_offset,
    const ui::ListSelectionModel& initial_selection_model,
    DetachBehavior detach_behavior,
    MoveBehavior move_behavior,
    EventSource event_source) {
  DCHECK(!tabs.empty());
  DCHECK(std::find(tabs.begin(), tabs.end(), source_tab) != tabs.end());
  source_tabstrip_ = source_tabstrip;
  was_source_maximized_ = source_tabstrip->GetWidget()->IsMaximized();
  was_source_fullscreen_ = source_tabstrip->GetWidget()->IsFullscreen();
  screen_ = gfx::Screen::GetScreenFor(
      source_tabstrip->GetWidget()->GetNativeView());
  host_desktop_type_ = chrome::GetHostDesktopTypeForNativeView(
      source_tabstrip->GetWidget()->GetNativeView());
#if defined(OS_LINUX)
  use_aura_capture_policy_ = true;
#else
  use_aura_capture_policy_ =
      (host_desktop_type_ == chrome::HOST_DESKTOP_TYPE_ASH);
#endif
  start_point_in_screen_ = gfx::Point(source_tab_offset, mouse_offset.y());
  views::View::ConvertPointToScreen(source_tab, &start_point_in_screen_);
  event_source_ = event_source;
  mouse_offset_ = mouse_offset;
  detach_behavior_ = detach_behavior;
  move_behavior_ = move_behavior;
  last_point_in_screen_ = start_point_in_screen_;
  last_move_screen_loc_ = start_point_in_screen_.x();
  initial_tab_positions_ = source_tabstrip->GetTabXCoordinates();
  if (detach_behavior == NOT_DETACHABLE)
    detach_into_browser_ = false;

  if (detach_into_browser_)
    GetModel(source_tabstrip_)->AddObserver(this);

  drag_data_.resize(tabs.size());
  for (size_t i = 0; i < tabs.size(); ++i)
    InitTabDragData(tabs[i], &(drag_data_[i]));
  source_tab_index_ =
      std::find(tabs.begin(), tabs.end(), source_tab) - tabs.begin();

  // Listen for Esc key presses.
  base::MessageLoopForUI::current()->AddObserver(this);

  if (source_tab->width() > 0) {
    offset_to_width_ratio_ = static_cast<float>(
        source_tab->GetMirroredXInView(source_tab_offset)) /
        static_cast<float>(source_tab->width());
  }
  InitWindowCreatePoint();
  initial_selection_model_.Copy(initial_selection_model);

  // Gestures don't automatically do a capture. We don't allow multiple drags at
  // the same time, so we explicitly capture.
  if (event_source == EVENT_SOURCE_TOUCH)
    source_tabstrip_->GetWidget()->SetCapture(source_tabstrip_);
}

// static
bool TabDragController::IsAttachedTo(const TabStrip* tab_strip) {
  return (instance_ && instance_->active() &&
          instance_->attached_tabstrip() == tab_strip);
}

// static
bool TabDragController::IsActive() {
  return instance_ && instance_->active();
}

void TabDragController::SetMoveBehavior(MoveBehavior behavior) {
  if (started_drag())
    return;

  move_behavior_ = behavior;
}

void TabDragController::Drag(const gfx::Point& point_in_screen) {
  TRACE_EVENT1("views", "TabDragController::Drag",
               "point_in_screen", point_in_screen.ToString());

  bring_to_front_timer_.Stop();
  move_stacked_timer_.Stop();

  if (waiting_for_run_loop_to_exit_)
    return;

  if (!started_drag_) {
    if (!CanStartDrag(point_in_screen))
      return;  // User hasn't dragged far enough yet.

    // On windows SaveFocus() may trigger a capture lost, which destroys us.
    {
      base::WeakPtr<TabDragController> ref(weak_factory_.GetWeakPtr());
      SaveFocus();
      if (!ref)
        return;
    }
    started_drag_ = true;
    Attach(source_tabstrip_, gfx::Point());
    if (detach_into_browser_ && static_cast<int>(drag_data_.size()) ==
        GetModel(source_tabstrip_)->count()) {
      if (was_source_maximized_ || was_source_fullscreen_) {
        did_restore_window_ = true;
        // When all tabs in a maximized browser are dragged the browser gets
        // restored during the drag and maximized back when the drag ends.
        views::Widget* widget = GetAttachedBrowserWidget();
        const int last_tabstrip_width = attached_tabstrip_->tab_area_width();
        std::vector<gfx::Rect> drag_bounds = CalculateBoundsForDraggedTabs();
        OffsetX(GetAttachedDragPoint(point_in_screen).x(), &drag_bounds);
        gfx::Rect new_bounds(CalculateDraggedBrowserBounds(source_tabstrip_,
                                                           point_in_screen,
                                                           &drag_bounds));
        new_bounds.Offset(-widget->GetRestoredBounds().x() +
                          point_in_screen.x() -
                          mouse_offset_.x(), 0);
        widget->SetVisibilityChangedAnimationsEnabled(false);
        widget->Restore();
        widget->SetBounds(new_bounds);
        AdjustBrowserAndTabBoundsForDrag(last_tabstrip_width,
                                         point_in_screen,
                                         &drag_bounds);
        widget->SetVisibilityChangedAnimationsEnabled(true);
      }
      RunMoveLoop(GetWindowOffset(point_in_screen));
      return;
    }
  }

  ContinueDragging(point_in_screen);
}

void TabDragController::EndDrag(EndDragReason reason) {
  TRACE_EVENT0("views", "TabDragController::EndDrag");

  // If we're dragging a window ignore capture lost since it'll ultimately
  // trigger the move loop to end and we'll revert the drag when RunMoveLoop()
  // finishes.
  if (reason == END_DRAG_CAPTURE_LOST && is_dragging_window_)
    return;
  EndDragImpl(reason != END_DRAG_COMPLETE && source_tabstrip_ ?
              CANCELED : NORMAL);
}

void TabDragController::InitTabDragData(Tab* tab,
                                        TabDragData* drag_data) {
  TRACE_EVENT0("views", "TabDragController::InitTabDragData");
  drag_data->source_model_index =
      source_tabstrip_->GetModelIndexOfTab(tab);
  drag_data->contents = GetModel(source_tabstrip_)->GetWebContentsAt(
      drag_data->source_model_index);
  drag_data->pinned = source_tabstrip_->IsTabPinned(tab);
  registrar_.Add(
      this,
      content::NOTIFICATION_WEB_CONTENTS_DESTROYED,
      content::Source<WebContents>(drag_data->contents));

  if (!detach_into_browser_) {
    drag_data->original_delegate = drag_data->contents->GetDelegate();
    drag_data->contents->SetDelegate(this);
  }
}

///////////////////////////////////////////////////////////////////////////////
// TabDragController, PageNavigator implementation:

WebContents* TabDragController::OpenURLFromTab(
    WebContents* source,
    const OpenURLParams& params) {
  if (source_tab_drag_data()->original_delegate) {
    OpenURLParams forward_params = params;
    if (params.disposition == CURRENT_TAB)
      forward_params.disposition = NEW_WINDOW;

    return source_tab_drag_data()->original_delegate->OpenURLFromTab(
        source, forward_params);
  }
  return NULL;
}

///////////////////////////////////////////////////////////////////////////////
// TabDragController, content::WebContentsDelegate implementation:

void TabDragController::NavigationStateChanged(const WebContents* source,
                                               unsigned changed_flags) {
  if (attached_tabstrip_ ||
      changed_flags == content::INVALIDATE_TYPE_PAGE_ACTIONS) {
    for (size_t i = 0; i < drag_data_.size(); ++i) {
      if (drag_data_[i].contents == source) {
        // Pass the NavigationStateChanged call to the original delegate so
        // that the title is updated. Do this only when we are attached as
        // otherwise the Tab isn't in the TabStrip (except for page action
        // updates).
        drag_data_[i].original_delegate->NavigationStateChanged(source,
                                                                changed_flags);
        break;
      }
    }
  }
}

void TabDragController::AddNewContents(WebContents* source,
                                       WebContents* new_contents,
                                       WindowOpenDisposition disposition,
                                       const gfx::Rect& initial_pos,
                                       bool user_gesture,
                                       bool* was_blocked) {
  DCHECK_NE(CURRENT_TAB, disposition);

  // Theoretically could be called while dragging if the page tries to
  // spawn a window. Route this message back to the browser in most cases.
  if (source_tab_drag_data()->original_delegate) {
    source_tab_drag_data()->original_delegate->AddNewContents(
        source, new_contents, disposition, initial_pos, user_gesture,
        was_blocked);
  }
}

bool TabDragController::ShouldSuppressDialogs() {
  // When a dialog is about to be shown we revert the drag. Otherwise a modal
  // dialog might appear and attempt to parent itself to a hidden tabcontents.
  EndDragImpl(CANCELED);
  return false;
}

content::JavaScriptDialogManager*
TabDragController::GetJavaScriptDialogManager() {
  return GetJavaScriptDialogManagerInstance();
}

void TabDragController::RequestMediaAccessPermission(
    content::WebContents* web_contents,
    const content::MediaStreamRequest& request,
    const content::MediaResponseCallback& callback) {
  ::RequestMediaAccessPermission(
      web_contents,
      Profile::FromBrowserContext(web_contents->GetBrowserContext()),
      request,
      callback);
}

///////////////////////////////////////////////////////////////////////////////
// TabDragController, content::NotificationObserver implementation:

void TabDragController::Observe(
    int type,
    const content::NotificationSource& source,
    const content::NotificationDetails& details) {
  DCHECK_EQ(content::NOTIFICATION_WEB_CONTENTS_DESTROYED, type);
  WebContents* destroyed_web_contents =
      content::Source<WebContents>(source).ptr();
  for (size_t i = 0; i < drag_data_.size(); ++i) {
    if (drag_data_[i].contents == destroyed_web_contents) {
      // One of the tabs we're dragging has been destroyed. Cancel the drag.
      if (destroyed_web_contents->GetDelegate() == this)
        destroyed_web_contents->SetDelegate(NULL);
      drag_data_[i].contents = NULL;
      drag_data_[i].original_delegate = NULL;
      EndDragImpl(TAB_DESTROYED);
      return;
    }
  }
  // If we get here it means we got notification for a tab we don't know about.
  NOTREACHED();
}

///////////////////////////////////////////////////////////////////////////////
// TabDragController, MessageLoop::Observer implementation:

base::EventStatus TabDragController::WillProcessEvent(
    const base::NativeEvent& event) {
  return base::EVENT_CONTINUE;
}

void TabDragController::DidProcessEvent(const base::NativeEvent& event) {
  // If the user presses ESC during a drag, we need to abort and revert things
  // to the way they were. This is the most reliable way to do this since no
  // single view or window reliably receives events throughout all the various
  // kinds of tab dragging.
  if (ui::EventTypeFromNative(event) == ui::ET_KEY_PRESSED &&
      ui::KeyboardCodeFromNative(event) == ui::VKEY_ESCAPE) {
    EndDrag(END_DRAG_CANCEL);
  }
}

void TabDragController::OnWidgetBoundsChanged(views::Widget* widget,
                                              const gfx::Rect& new_bounds) {
  TRACE_EVENT1("views", "TabDragController::OnWidgetBoundsChanged",
               "new_bounds", new_bounds.ToString());

  Drag(GetCursorScreenPoint());
}

void TabDragController::TabStripEmpty() {
  DCHECK(detach_into_browser_);
  GetModel(source_tabstrip_)->RemoveObserver(this);
  // NULL out source_tabstrip_ so that we don't attempt to add back to it (in
  // the case of a revert).
  source_tabstrip_ = NULL;
}

///////////////////////////////////////////////////////////////////////////////
// TabDragController, private:

void TabDragController::InitWindowCreatePoint() {
  // window_create_point_ is only used in CompleteDrag() (through
  // GetWindowCreatePoint() to get the start point of the docked window) when
  // the attached_tabstrip_ is NULL and all the window's related bound
  // information are obtained from source_tabstrip_. So, we need to get the
  // first_tab based on source_tabstrip_, not attached_tabstrip_. Otherwise,
  // the window_create_point_ is not in the correct coordinate system. Please
  // refer to http://crbug.com/6223 comment #15 for detailed information.
  views::View* first_tab = source_tabstrip_->tab_at(0);
  views::View::ConvertPointToWidget(first_tab, &first_source_tab_point_);
  window_create_point_ = first_source_tab_point_;
  window_create_point_.Offset(mouse_offset_.x(), mouse_offset_.y());
}

gfx::Point TabDragController::GetWindowCreatePoint(
    const gfx::Point& origin) const {
  // If the cursor is outside the monitor area, move it inside. For example,
  // dropping a tab onto the task bar on Windows produces this situation.
  gfx::Rect work_area = screen_->GetDisplayNearestPoint(origin).work_area();
  gfx::Point create_point(origin);
  if (!work_area.IsEmpty()) {
    if (create_point.x() < work_area.x())
      create_point.set_x(work_area.x());
    else if (create_point.x() > work_area.right())
      create_point.set_x(work_area.right());
    if (create_point.y() < work_area.y())
      create_point.set_y(work_area.y());
    else if (create_point.y() > work_area.bottom())
      create_point.set_y(work_area.bottom());
  }
  return gfx::Point(create_point.x() - window_create_point_.x(),
                    create_point.y() - window_create_point_.y());
}

void TabDragController::SaveFocus() {
  DCHECK(source_tabstrip_);
  views::View* focused_view =
      source_tabstrip_->GetFocusManager()->GetFocusedView();
  if (focused_view)
    views::ViewStorage::GetInstance()->StoreView(old_focused_view_id_,
                                                 focused_view);
  source_tabstrip_->GetFocusManager()->SetFocusedView(source_tabstrip_);
  // WARNING: we may have been deleted.
}

void TabDragController::RestoreFocus() {
  if (attached_tabstrip_ != source_tabstrip_) {
    if (is_dragging_new_browser_) {
      content::WebContents* active_contents = source_dragged_contents();
      if (active_contents && !active_contents->FocusLocationBarByDefault())
        active_contents->GetView()->Focus();
    }
    return;
  }
  views::View* old_focused_view =
      views::ViewStorage::GetInstance()->RetrieveView(old_focused_view_id_);
  if (!old_focused_view)
    return;
  old_focused_view->GetFocusManager()->SetFocusedView(old_focused_view);
}

bool TabDragController::CanStartDrag(const gfx::Point& point_in_screen) const {
  // Determine if the mouse has moved beyond a minimum elasticity distance in
  // any direction from the starting point.
  static const int kMinimumDragDistance = 10;
  int x_offset = abs(point_in_screen.x() - start_point_in_screen_.x());
  int y_offset = abs(point_in_screen.y() - start_point_in_screen_.y());
  return sqrt(pow(static_cast<float>(x_offset), 2) +
              pow(static_cast<float>(y_offset), 2)) > kMinimumDragDistance;
}

void TabDragController::ContinueDragging(const gfx::Point& point_in_screen) {
  TRACE_EVENT1("views", "TabDragController::ContinueDragging",
               "point_in_screen", point_in_screen.ToString());

  DCHECK(!detach_into_browser_ || attached_tabstrip_);

  TabStrip* target_tabstrip = detach_behavior_ == DETACHABLE ?
      GetTargetTabStripForPoint(point_in_screen) : source_tabstrip_;
  bool tab_strip_changed = (target_tabstrip != attached_tabstrip_);

  if (attached_tabstrip_) {
    int move_delta = point_in_screen.x() - last_point_in_screen_.x();
    if (move_delta > 0)
      mouse_move_direction_ |= kMovedMouseRight;
    else if (move_delta < 0)
      mouse_move_direction_ |= kMovedMouseLeft;
  }
  last_point_in_screen_ = point_in_screen;

  if (tab_strip_changed) {
    is_dragging_new_browser_ = false;
    did_restore_window_ = false;
    if (detach_into_browser_ &&
        DragBrowserToNewTabStrip(target_tabstrip, point_in_screen) ==
        DRAG_BROWSER_RESULT_STOP) {
      return;
    } else if (!detach_into_browser_) {
      if (attached_tabstrip_)
        Detach(RELEASE_CAPTURE);
      if (target_tabstrip)
        Attach(target_tabstrip, point_in_screen);
    }
  }
  if (is_dragging_window_) {
    static_cast<base::Timer*>(&bring_to_front_timer_)->Start(FROM_HERE,
        base::TimeDelta::FromMilliseconds(kBringToFrontDelay),
        base::Bind(&TabDragController::BringWindowUnderPointToFront,
                   base::Unretained(this), point_in_screen));
  }

  if (!is_dragging_window_ && attached_tabstrip_) {
    if (move_only()) {
      DragActiveTabStacked(point_in_screen);
    } else {
      MoveAttached(point_in_screen);
      if (tab_strip_changed) {
        // Move the corresponding window to the front. We do this after the
        // move as on windows activate triggers a synchronous paint.
        attached_tabstrip_->GetWidget()->Activate();
      }
    }
  }
}

TabDragController::DragBrowserResultType
TabDragController::DragBrowserToNewTabStrip(
    TabStrip* target_tabstrip,
    const gfx::Point& point_in_screen) {
  TRACE_EVENT1("views", "TabDragController::DragBrowserToNewTabStrip",
               "point_in_screen", point_in_screen.ToString());

  if (!target_tabstrip) {
    DetachIntoNewBrowserAndRunMoveLoop(point_in_screen);
    return DRAG_BROWSER_RESULT_STOP;
  }
  if (is_dragging_window_) {
    // ReleaseCapture() is going to result in calling back to us (because it
    // results in a move). That'll cause all sorts of problems.  Reset the
    // observer so we don't get notified and process the event.
    if (use_aura_capture_policy_) {
      move_loop_widget_->RemoveObserver(this);
      move_loop_widget_ = NULL;
    }
    views::Widget* browser_widget = GetAttachedBrowserWidget();
    // Need to release the drag controller before starting the move loop as it's
    // going to trigger capture lost, which cancels drag.
    attached_tabstrip_->ReleaseDragController();
    target_tabstrip->OwnDragController(this);
    // Disable animations so that we don't see a close animation on aero.
    browser_widget->SetVisibilityChangedAnimationsEnabled(false);
    // For aura we can't release capture, otherwise it'll cancel a gesture.
    // Instead we have to directly change capture.
    if (use_aura_capture_policy_)
      target_tabstrip->GetWidget()->SetCapture(attached_tabstrip_);
    else
      browser_widget->ReleaseCapture();
#if defined(OS_WIN)
    // The Gesture recognizer does not work well currently when capture changes
    // while a touch gesture is in progress. So we need to manually transfer
    // gesture sequence and the GR's touch events queue to the new window. This
    // should really be done somewhere in capture change code and or inside the
    // GR. But we currently do not have a consistent way for doing it that would
    // work in all cases. Hence this hack.
    ui::GestureRecognizer::Get()->TransferEventsTo(
        browser_widget->GetNativeView(),
        target_tabstrip->GetWidget()->GetNativeView());
#endif

    // The window is going away. Since the drag is still on going we don't want
    // that to effect the position of any windows.
    SetWindowPositionManaged(browser_widget->GetNativeView(), false);

#if !defined(OS_LINUX) || defined(OS_CHROMEOS)
    // EndMoveLoop is going to snap the window back to its original location.
    // Hide it so users don't see this. Hiding a window in Linux aura causes
    // it to lose capture so skip it.
    browser_widget->Hide();
#endif
    browser_widget->EndMoveLoop();

    // Ideally we would always swap the tabs now, but on non-ash it seems that
    // running the move loop implicitly activates the window when done, leading
    // to all sorts of flicker. So, on non-ash, instead we process the move
    // after the loop completes. But on chromeos, we can do tab swapping now to
    // avoid the tab flashing issue(crbug.com/116329).
    if (use_aura_capture_policy_) {
      is_dragging_window_ = false;
      Detach(DONT_RELEASE_CAPTURE);
      Attach(target_tabstrip, point_in_screen);
      // Move the tabs into position.
      MoveAttached(point_in_screen);
      attached_tabstrip_->GetWidget()->Activate();
    } else {
      tab_strip_to_attach_to_after_exit_ = target_tabstrip;
    }

    waiting_for_run_loop_to_exit_ = true;
    end_run_loop_behavior_ = END_RUN_LOOP_CONTINUE_DRAGGING;
    return DRAG_BROWSER_RESULT_STOP;
  }
  Detach(DONT_RELEASE_CAPTURE);
  Attach(target_tabstrip, point_in_screen);
  return DRAG_BROWSER_RESULT_CONTINUE;
}

void TabDragController::DragActiveTabStacked(
    const gfx::Point& point_in_screen) {
  if (attached_tabstrip_->tab_count() !=
      static_cast<int>(initial_tab_positions_.size()))
    return;  // TODO: should cancel drag if this happens.

  int delta = point_in_screen.x() - start_point_in_screen_.x();
  attached_tabstrip_->DragActiveTab(initial_tab_positions_, delta);
}

void TabDragController::MoveAttachedToNextStackedIndex(
    const gfx::Point& point_in_screen) {
  int index = attached_tabstrip_->touch_layout_->active_index();
  if (index + 1 >= attached_tabstrip_->tab_count())
    return;

  GetModel(attached_tabstrip_)->MoveSelectedTabsTo(index + 1);
  StartMoveStackedTimerIfNecessary(point_in_screen,
                                   kMoveAttachedSubsequentDelay);
}

void TabDragController::MoveAttachedToPreviousStackedIndex(
    const gfx::Point& point_in_screen) {
  int index = attached_tabstrip_->touch_layout_->active_index();
  if (index <= attached_tabstrip_->GetMiniTabCount())
    return;

  GetModel(attached_tabstrip_)->MoveSelectedTabsTo(index - 1);
  StartMoveStackedTimerIfNecessary(point_in_screen,
                                   kMoveAttachedSubsequentDelay);
}

void TabDragController::MoveAttached(const gfx::Point& point_in_screen) {
  DCHECK(attached_tabstrip_);
  DCHECK(!is_dragging_window_);

  gfx::Point dragged_view_point = GetAttachedDragPoint(point_in_screen);

  // Determine the horizontal move threshold. This is dependent on the width
  // of tabs. The smaller the tabs compared to the standard size, the smaller
  // the threshold.
  int threshold = kHorizontalMoveThreshold;
  if (!attached_tabstrip_->touch_layout_.get()) {
    double unselected, selected;
    attached_tabstrip_->GetCurrentTabWidths(&unselected, &selected);
    double ratio = unselected / Tab::GetStandardSize().width();
    threshold = static_cast<int>(ratio * kHorizontalMoveThreshold);
  }
  // else case: touch tabs never shrink.

  std::vector<Tab*> tabs(drag_data_.size());
  for (size_t i = 0; i < drag_data_.size(); ++i)
    tabs[i] = drag_data_[i].attached_tab;

  bool did_layout = false;
  // Update the model, moving the WebContents from one index to another. Do this
  // only if we have moved a minimum distance since the last reorder (to prevent
  // jitter) or if this the first move and the tabs are not consecutive.
  if ((abs(point_in_screen.x() - last_move_screen_loc_) > threshold ||
        (initial_move_ && !AreTabsConsecutive()))) {
    TabStripModel* attached_model = GetModel(attached_tabstrip_);
    gfx::Rect bounds = GetDraggedViewTabStripBounds(dragged_view_point);
    int to_index = GetInsertionIndexForDraggedBounds(bounds);
    bool do_move = true;
    // While dragging within a tabstrip the expectation is the insertion index
    // is based on the left edge of the tabs being dragged. OTOH when dragging
    // into a new tabstrip (attaching) the expectation is the insertion index is
    // based on the cursor. This proves problematic as insertion may change the
    // size of the tabs, resulting in the index calculated before the insert
    // differing from the index calculated after the insert. To alleviate this
    // the index is chosen before insertion, and subsequently a new index is
    // only used once the mouse moves enough such that the index changes based
    // on the direction the mouse moved relative to |attach_x_| (smaller
    // x-coordinate should yield a smaller index or larger x-coordinate yields a
    // larger index).
    if (attach_index_ != -1) {
      gfx::Point tab_strip_point(point_in_screen);
      views::View::ConvertPointFromScreen(attached_tabstrip_, &tab_strip_point);
      const int new_x =
          attached_tabstrip_->GetMirroredXInView(tab_strip_point.x());
      if (new_x < attach_x_)
        to_index = std::min(to_index, attach_index_);
      else
        to_index = std::max(to_index, attach_index_);
      if (to_index != attach_index_)
        attach_index_ = -1;  // Once a valid move is detected, don't constrain.
      else
        do_move = false;
    }
    if (do_move) {
      WebContents* last_contents = drag_data_[drag_data_.size() - 1].contents;
      int index_of_last_item =
          attached_model->GetIndexOfWebContents(last_contents);
      if (initial_move_) {
        // TabStrip determines if the tabs needs to be animated based on model
        // position. This means we need to invoke LayoutDraggedTabsAt before
        // changing the model.
        attached_tabstrip_->LayoutDraggedTabsAt(
            tabs, source_tab_drag_data()->attached_tab, dragged_view_point,
            initial_move_);
        did_layout = true;
      }
      attached_model->MoveSelectedTabsTo(to_index);

      // Move may do nothing in certain situations (such as when dragging pinned
      // tabs). Make sure the tabstrip actually changed before updating
      // last_move_screen_loc_.
      if (index_of_last_item !=
          attached_model->GetIndexOfWebContents(last_contents)) {
        last_move_screen_loc_ = point_in_screen.x();
      }
    }
  }

  if (!did_layout) {
    attached_tabstrip_->LayoutDraggedTabsAt(
        tabs, source_tab_drag_data()->attached_tab, dragged_view_point,
        initial_move_);
  }

  StartMoveStackedTimerIfNecessary(point_in_screen, kMoveAttachedInitialDelay);

  initial_move_ = false;
}

void TabDragController::StartMoveStackedTimerIfNecessary(
    const gfx::Point& point_in_screen,
    int delay_ms) {
  DCHECK(attached_tabstrip_);

  StackedTabStripLayout* touch_layout = attached_tabstrip_->touch_layout_.get();
  if (!touch_layout)
    return;

  gfx::Point dragged_view_point = GetAttachedDragPoint(point_in_screen);
  gfx::Rect bounds = GetDraggedViewTabStripBounds(dragged_view_point);
  int index = touch_layout->active_index();
  if (ShouldDragToNextStackedTab(bounds, index)) {
    static_cast<base::Timer*>(&move_stacked_timer_)->Start(
        FROM_HERE,
        base::TimeDelta::FromMilliseconds(delay_ms),
        base::Bind(&TabDragController::MoveAttachedToNextStackedIndex,
                   base::Unretained(this), point_in_screen));
  } else if (ShouldDragToPreviousStackedTab(bounds, index)) {
    static_cast<base::Timer*>(&move_stacked_timer_)->Start(
        FROM_HERE,
        base::TimeDelta::FromMilliseconds(delay_ms),
        base::Bind(&TabDragController::MoveAttachedToPreviousStackedIndex,
                   base::Unretained(this), point_in_screen));
  }
}

TabDragController::DetachPosition TabDragController::GetDetachPosition(
    const gfx::Point& point_in_screen) {
  DCHECK(attached_tabstrip_);
  gfx::Point attached_point(point_in_screen);
  views::View::ConvertPointFromScreen(attached_tabstrip_, &attached_point);
  if (attached_point.x() < 0)
    return DETACH_BEFORE;
  if (attached_point.x() >= attached_tabstrip_->width())
    return DETACH_AFTER;
  return DETACH_ABOVE_OR_BELOW;
}

TabStrip* TabDragController::GetTargetTabStripForPoint(
    const gfx::Point& point_in_screen) {
  TRACE_EVENT1("views", "TabDragController::GetTargetTabStripForPoint",
               "point_in_screen", point_in_screen.ToString());

  if (move_only() && attached_tabstrip_) {
    DCHECK_EQ(DETACHABLE, detach_behavior_);
    // move_only() is intended for touch, in which case we only want to detach
    // if the touch point moves significantly in the vertical distance.
    gfx::Rect tabstrip_bounds = GetViewScreenBounds(attached_tabstrip_);
    if (DoesRectContainVerticalPointExpanded(tabstrip_bounds,
                                             kTouchVerticalDetachMagnetism,
                                             point_in_screen.y()))
      return attached_tabstrip_;
  }
  gfx::NativeWindow local_window =
      GetLocalProcessWindow(point_in_screen, is_dragging_window_);
  TabStrip* tab_strip = GetTabStripForWindow(local_window);
  if (tab_strip && DoesTabStripContain(tab_strip, point_in_screen))
    return tab_strip;
  return is_dragging_window_ ? attached_tabstrip_ : NULL;
}

TabStrip* TabDragController::GetTabStripForWindow(gfx::NativeWindow window) {
  if (!window)
    return NULL;
  BrowserView* browser_view =
      BrowserView::GetBrowserViewForNativeWindow(window);
  // We don't allow drops on windows that don't have tabstrips.
  if (!browser_view ||
      !browser_view->browser()->SupportsWindowFeature(
          Browser::FEATURE_TABSTRIP))
    return NULL;

  TabStrip* other_tabstrip = browser_view->tabstrip();
  TabStrip* tab_strip =
      attached_tabstrip_ ? attached_tabstrip_ : source_tabstrip_;
  DCHECK(tab_strip);

  return other_tabstrip->controller()->IsCompatibleWith(tab_strip) ?
      other_tabstrip : NULL;
}

bool TabDragController::DoesTabStripContain(
    TabStrip* tabstrip,
    const gfx::Point& point_in_screen) const {
  // Make sure the specified screen point is actually within the bounds of the
  // specified tabstrip...
  gfx::Rect tabstrip_bounds = GetViewScreenBounds(tabstrip);
  return point_in_screen.x() < tabstrip_bounds.right() &&
      point_in_screen.x() >= tabstrip_bounds.x() &&
      DoesRectContainVerticalPointExpanded(tabstrip_bounds,
                                           kVerticalDetachMagnetism,
                                           point_in_screen.y());
}

void TabDragController::Attach(TabStrip* attached_tabstrip,
                               const gfx::Point& point_in_screen) {
  TRACE_EVENT1("views", "TabDragController::Attach",
               "point_in_screen", point_in_screen.ToString());

  DCHECK(!attached_tabstrip_);  // We should already have detached by the time
                                // we get here.

  attached_tabstrip_ = attached_tabstrip;

  std::vector<Tab*> tabs =
      GetTabsMatchingDraggedContents(attached_tabstrip_);

  if (tabs.empty()) {
    // Transitioning from detached to attached to a new tabstrip. Add tabs to
    // the new model.

    selection_model_before_attach_.Copy(attached_tabstrip->GetSelectionModel());

    if (!detach_into_browser_) {
      // Remove ourselves as the delegate now that the dragged WebContents is
      // being inserted back into a Browser.
      for (size_t i = 0; i < drag_data_.size(); ++i) {
        drag_data_[i].contents->SetDelegate(NULL);
        drag_data_[i].original_delegate = NULL;
      }

      // Return the WebContents to normalcy.
      source_dragged_contents()->DecrementCapturerCount();
    }

    // Inserting counts as a move. We don't want the tabs to jitter when the
    // user moves the tab immediately after attaching it.
    last_move_screen_loc_ = point_in_screen.x();

    // Figure out where to insert the tab based on the bounds of the dragged
    // representation and the ideal bounds of the other Tabs already in the
    // strip. ("ideal bounds" are stable even if the Tabs' actual bounds are
    // changing due to animation).
    gfx::Point tab_strip_point(point_in_screen);
    views::View::ConvertPointFromScreen(attached_tabstrip_, &tab_strip_point);
    tab_strip_point.set_x(
        attached_tabstrip_->GetMirroredXInView(tab_strip_point.x()));
    tab_strip_point.Offset(0, -mouse_offset_.y());
    gfx::Rect bounds = GetDraggedViewTabStripBounds(tab_strip_point);
    int index = GetInsertionIndexForDraggedBounds(bounds);
    attach_index_ = index;
    attach_x_ = tab_strip_point.x();
    base::AutoReset<bool> setter(&is_mutating_, true);
    for (size_t i = 0; i < drag_data_.size(); ++i) {
      int add_types = TabStripModel::ADD_NONE;
      if (attached_tabstrip_->touch_layout_.get()) {
        // StackedTabStripLayout positions relative to the active tab, if we
        // don't add the tab as active things bounce around.
        DCHECK_EQ(1u, drag_data_.size());
        add_types |= TabStripModel::ADD_ACTIVE;
      }
      if (drag_data_[i].pinned)
        add_types |= TabStripModel::ADD_PINNED;
      GetModel(attached_tabstrip_)->InsertWebContentsAt(
          index + i, drag_data_[i].contents, add_types);
    }

    tabs = GetTabsMatchingDraggedContents(attached_tabstrip_);
  }
  DCHECK_EQ(tabs.size(), drag_data_.size());
  for (size_t i = 0; i < drag_data_.size(); ++i)
    drag_data_[i].attached_tab = tabs[i];

  attached_tabstrip_->StartedDraggingTabs(tabs);

  ResetSelection(GetModel(attached_tabstrip_));

  // The size of the dragged tab may have changed. Adjust the x offset so that
  // ratio of mouse_offset_ to original width is maintained.
  std::vector<Tab*> tabs_to_source(tabs);
  tabs_to_source.erase(tabs_to_source.begin() + source_tab_index_ + 1,
                       tabs_to_source.end());
  int new_x = attached_tabstrip_->GetSizeNeededForTabs(tabs_to_source) -
      tabs[source_tab_index_]->width() +
      static_cast<int>(offset_to_width_ratio_ *
                       tabs[source_tab_index_]->width());
  mouse_offset_.set_x(new_x);

  // Transfer ownership of us to the new tabstrip as well as making sure the
  // window has capture. This is important so that if activation changes the
  // drag isn't prematurely canceled.
  if (detach_into_browser_) {
    attached_tabstrip_->GetWidget()->SetCapture(attached_tabstrip_);
    attached_tabstrip_->OwnDragController(this);
  }

  // Redirect all mouse events to the TabStrip so that the tab that originated
  // the drag can safely be deleted.
  if (detach_into_browser_ || attached_tabstrip_ == source_tabstrip_) {
    static_cast<views::internal::RootView*>(
        attached_tabstrip_->GetWidget()->GetRootView())->SetMouseHandler(
            attached_tabstrip_);
  }
}

void TabDragController::Detach(ReleaseCapture release_capture) {
  TRACE_EVENT1("views", "TabDragController::Detach",
               "release_capture", release_capture);

  attach_index_ = -1;

  // When the user detaches we assume they want to reorder.
  move_behavior_ = REORDER;

  // Release ownership of the drag controller and mouse capture. When we
  // reattach ownership is transfered.
  if (detach_into_browser_) {
    attached_tabstrip_->ReleaseDragController();
    if (release_capture == RELEASE_CAPTURE)
      attached_tabstrip_->GetWidget()->ReleaseCapture();
  }

  mouse_move_direction_ = kMovedMouseLeft | kMovedMouseRight;

  // Prevent the WebContents HWND from being hidden by any of the model
  // operations performed during the drag.
  if (!detach_into_browser_)
    source_dragged_contents()->IncrementCapturerCount(gfx::Size());

  std::vector<gfx::Rect> drag_bounds = CalculateBoundsForDraggedTabs();
  TabStripModel* attached_model = GetModel(attached_tabstrip_);
  std::vector<TabRendererData> tab_data;
  for (size_t i = 0; i < drag_data_.size(); ++i) {
    tab_data.push_back(drag_data_[i].attached_tab->data());
    int index = attached_model->GetIndexOfWebContents(drag_data_[i].contents);
    DCHECK_NE(-1, index);

    // Hide the tab so that the user doesn't see it animate closed.
    drag_data_[i].attached_tab->SetVisible(false);

    attached_model->DetachWebContentsAt(index);

    // Detaching resets the delegate, but we still want to be the delegate.
    if (!detach_into_browser_)
      drag_data_[i].contents->SetDelegate(this);

    // Detaching may end up deleting the tab, drop references to it.
    drag_data_[i].attached_tab = NULL;
  }

  // If we've removed the last Tab from the TabStrip, hide the frame now.
  if (!attached_model->empty()) {
    if (!selection_model_before_attach_.empty() &&
        selection_model_before_attach_.active() >= 0 &&
        selection_model_before_attach_.active() < attached_model->count()) {
      // Restore the selection.
      attached_model->SetSelectionFromModel(selection_model_before_attach_);
    } else if (attached_tabstrip_ == source_tabstrip_ &&
               !initial_selection_model_.empty()) {
      RestoreInitialSelection();
    }
  }

  attached_tabstrip_->DraggedTabsDetached();
  attached_tabstrip_ = NULL;
}

void TabDragController::DetachIntoNewBrowserAndRunMoveLoop(
    const gfx::Point& point_in_screen) {
  if (GetModel(attached_tabstrip_)->count() ==
      static_cast<int>(drag_data_.size())) {
    // All the tabs in a browser are being dragged but all the tabs weren't
    // initially being dragged. For this to happen the user would have to
    // start dragging a set of tabs, the other tabs close, then detach.
    RunMoveLoop(GetWindowOffset(point_in_screen));
    return;
  }

  const int last_tabstrip_width = attached_tabstrip_->tab_area_width();
  std::vector<gfx::Rect> drag_bounds = CalculateBoundsForDraggedTabs();
  OffsetX(GetAttachedDragPoint(point_in_screen).x(), &drag_bounds);

  gfx::Vector2d drag_offset;
  Browser* browser = CreateBrowserForDrag(
      attached_tabstrip_, point_in_screen, &drag_offset, &drag_bounds);
#if defined(OS_WIN)
  gfx::NativeView attached_native_view =
    attached_tabstrip_->GetWidget()->GetNativeView();
#endif
  Detach(use_aura_capture_policy_ ? DONT_RELEASE_CAPTURE : RELEASE_CAPTURE);
  BrowserView* dragged_browser_view =
      BrowserView::GetBrowserViewForBrowser(browser);
  views::Widget* dragged_widget = dragged_browser_view->GetWidget();
#if defined(OS_WIN)
    // The Gesture recognizer does not work well currently when capture changes
    // while a touch gesture is in progress. So we need to manually transfer
    // gesture sequence and the GR's touch events queue to the new window. This
    // should really be done somewhere in capture change code and or inside the
    // GR. But we currently do not have a consistent way for doing it that would
    // work in all cases. Hence this hack.
    ui::GestureRecognizer::Get()->TransferEventsTo(
        attached_native_view,
        dragged_widget->GetNativeView());
#endif
  dragged_widget->SetVisibilityChangedAnimationsEnabled(false);
  Attach(dragged_browser_view->tabstrip(), gfx::Point());
  AdjustBrowserAndTabBoundsForDrag(last_tabstrip_width,
                                   point_in_screen,
                                   &drag_bounds);
  WindowPositionManagedUpdater updater;
  dragged_widget->AddObserver(&updater);
  browser->window()->Show();
  dragged_widget->RemoveObserver(&updater);
  dragged_widget->SetVisibilityChangedAnimationsEnabled(true);
  // Activate may trigger a focus loss, destroying us.
  {
    base::WeakPtr<TabDragController> ref(weak_factory_.GetWeakPtr());
    browser->window()->Activate();
    if (!ref)
      return;
  }
  RunMoveLoop(drag_offset);
}

void TabDragController::RunMoveLoop(const gfx::Vector2d& drag_offset) {
  // If the user drags the whole window we'll assume they are going to attach to
  // another window and therefore want to reorder.
  move_behavior_ = REORDER;

  move_loop_widget_ = GetAttachedBrowserWidget();
  DCHECK(move_loop_widget_);
  move_loop_widget_->AddObserver(this);
  is_dragging_window_ = true;
  base::WeakPtr<TabDragController> ref(weak_factory_.GetWeakPtr());
  // Running the move loop releases mouse capture on non-ash, which triggers
  // destroying the drag loop. Release mouse capture ourself before this while
  // the DragController isn't owned by the TabStrip.
  if (host_desktop_type_ != chrome::HOST_DESKTOP_TYPE_ASH) {
    attached_tabstrip_->ReleaseDragController();
    attached_tabstrip_->GetWidget()->ReleaseCapture();
    attached_tabstrip_->OwnDragController(this);
  }
  const views::Widget::MoveLoopSource move_loop_source =
      event_source_ == EVENT_SOURCE_MOUSE ?
      views::Widget::MOVE_LOOP_SOURCE_MOUSE :
      views::Widget::MOVE_LOOP_SOURCE_TOUCH;
  const views::Widget::MoveLoopEscapeBehavior escape_behavior =
      is_dragging_new_browser_ ?
          views::Widget::MOVE_LOOP_ESCAPE_BEHAVIOR_HIDE :
          views::Widget::MOVE_LOOP_ESCAPE_BEHAVIOR_DONT_HIDE;
  views::Widget::MoveLoopResult result =
      move_loop_widget_->RunMoveLoop(
          drag_offset, move_loop_source, escape_behavior);
  content::NotificationService::current()->Notify(
      chrome::NOTIFICATION_TAB_DRAG_LOOP_DONE,
      content::NotificationService::AllBrowserContextsAndSources(),
      content::NotificationService::NoDetails());

  if (!ref)
    return;
  // Under chromeos we immediately set the |move_loop_widget_| to NULL.
  if (move_loop_widget_) {
    move_loop_widget_->RemoveObserver(this);
    move_loop_widget_ = NULL;
  }
  is_dragging_window_ = false;
  waiting_for_run_loop_to_exit_ = false;
  if (end_run_loop_behavior_ == END_RUN_LOOP_CONTINUE_DRAGGING) {
    end_run_loop_behavior_ = END_RUN_LOOP_STOP_DRAGGING;
    if (tab_strip_to_attach_to_after_exit_) {
      gfx::Point point_in_screen(GetCursorScreenPoint());
      Detach(DONT_RELEASE_CAPTURE);
      Attach(tab_strip_to_attach_to_after_exit_, point_in_screen);
      // Move the tabs into position.
      MoveAttached(point_in_screen);
      attached_tabstrip_->GetWidget()->Activate();
      // Activate may trigger a focus loss, destroying us.
      if (!ref)
        return;
      tab_strip_to_attach_to_after_exit_ = NULL;
    }
    DCHECK(attached_tabstrip_);
    attached_tabstrip_->GetWidget()->SetCapture(attached_tabstrip_);
  } else if (active_) {
    EndDrag(result == views::Widget::MOVE_LOOP_CANCELED ?
            END_DRAG_CANCEL : END_DRAG_COMPLETE);
  }
}

int TabDragController::GetInsertionIndexFrom(const gfx::Rect& dragged_bounds,
                                             int start,
                                             int delta) const {
  for (int i = start, tab_count = attached_tabstrip_->tab_count();
       i >= 0 && i < tab_count; i += delta) {
    const gfx::Rect& ideal_bounds = attached_tabstrip_->ideal_bounds(i);
    gfx::Rect left_half, right_half;
    ideal_bounds.SplitVertically(&left_half, &right_half);
    if (dragged_bounds.x() >= right_half.x() &&
        dragged_bounds.x() < right_half.right()) {
      return i + 1;
    } else if (dragged_bounds.x() >= left_half.x() &&
               dragged_bounds.x() < left_half.right()) {
      return i;
    }
  }
  return -1;
}

int TabDragController::GetInsertionIndexForDraggedBounds(
    const gfx::Rect& dragged_bounds) const {
  int index = -1;
  if (attached_tabstrip_->touch_layout_.get()) {
    index = GetInsertionIndexForDraggedBoundsStacked(dragged_bounds);
    if (index != -1) {
      // Only move the tab to the left/right if the user actually moved the
      // mouse that way. This is necessary as tabs with stacked tabs
      // before/after them have multiple drag positions.
      int active_index = attached_tabstrip_->touch_layout_->active_index();
      if ((index < active_index &&
           (mouse_move_direction_ & kMovedMouseLeft) == 0) ||
          (index > active_index &&
           (mouse_move_direction_ & kMovedMouseRight) == 0)) {
        index = active_index;
      }
    }
  } else {
    index = GetInsertionIndexFrom(dragged_bounds, 0, 1);
  }
  if (index == -1) {
    int tab_count = attached_tabstrip_->tab_count();
    int right_tab_x = tab_count == 0 ? 0 :
        attached_tabstrip_->ideal_bounds(tab_count - 1).right();
    if (dragged_bounds.right() > right_tab_x) {
      index = GetModel(attached_tabstrip_)->count();
    } else {
      index = 0;
    }
  }

  if (!drag_data_[0].attached_tab) {
    // If 'attached_tab' is NULL, it means we're in the process of attaching and
    // don't need to constrain the index.
    return index;
  }

  int max_index = GetModel(attached_tabstrip_)->count() -
      static_cast<int>(drag_data_.size());
  return std::max(0, std::min(max_index, index));
}

bool TabDragController::ShouldDragToNextStackedTab(
    const gfx::Rect& dragged_bounds,
    int index) const {
  if (index + 1 >= attached_tabstrip_->tab_count() ||
      !attached_tabstrip_->touch_layout_->IsStacked(index + 1) ||
      (mouse_move_direction_ & kMovedMouseRight) == 0)
    return false;

  int active_x = attached_tabstrip_->ideal_bounds(index).x();
  int next_x = attached_tabstrip_->ideal_bounds(index + 1).x();
  int mid_x = std::min(next_x - kStackedDistance,
                       active_x + (next_x - active_x) / 4);
  return dragged_bounds.x() >= mid_x;
}

bool TabDragController::ShouldDragToPreviousStackedTab(
    const gfx::Rect& dragged_bounds,
    int index) const {
  if (index - 1 < attached_tabstrip_->GetMiniTabCount() ||
      !attached_tabstrip_->touch_layout_->IsStacked(index - 1) ||
      (mouse_move_direction_ & kMovedMouseLeft) == 0)
    return false;

  int active_x = attached_tabstrip_->ideal_bounds(index).x();
  int previous_x = attached_tabstrip_->ideal_bounds(index - 1).x();
  int mid_x = std::max(previous_x + kStackedDistance,
                       active_x - (active_x - previous_x) / 4);
  return dragged_bounds.x() <= mid_x;
}

int TabDragController::GetInsertionIndexForDraggedBoundsStacked(
    const gfx::Rect& dragged_bounds) const {
  StackedTabStripLayout* touch_layout = attached_tabstrip_->touch_layout_.get();
  int active_index = touch_layout->active_index();
  // Search from the active index to the front of the tabstrip. Do this as tabs
  // overlap each other from the active index.
  int index = GetInsertionIndexFrom(dragged_bounds, active_index, -1);
  if (index != active_index)
    return index;
  if (index == -1)
    return GetInsertionIndexFrom(dragged_bounds, active_index + 1, 1);

  // The position to drag to corresponds to the active tab. If the next/previous
  // tab is stacked, then shorten the distance used to determine insertion
  // bounds. We do this as GetInsertionIndexFrom() uses the bounds of the
  // tabs. When tabs are stacked the next/previous tab is on top of the tab.
  if (active_index + 1 < attached_tabstrip_->tab_count() &&
      touch_layout->IsStacked(active_index + 1)) {
    index = GetInsertionIndexFrom(dragged_bounds, active_index + 1, 1);
    if (index == -1 && ShouldDragToNextStackedTab(dragged_bounds, active_index))
      index = active_index + 1;
    else if (index == -1)
      index = active_index;
  } else if (ShouldDragToPreviousStackedTab(dragged_bounds, active_index)) {
    index = active_index - 1;
  }
  return index;
}

gfx::Rect TabDragController::GetDraggedViewTabStripBounds(
    const gfx::Point& tab_strip_point) {
  // attached_tab is NULL when inserting into a new tabstrip.
  if (source_tab_drag_data()->attached_tab) {
    return gfx::Rect(tab_strip_point.x(), tab_strip_point.y(),
                     source_tab_drag_data()->attached_tab->width(),
                     source_tab_drag_data()->attached_tab->height());
  }

  double sel_width, unselected_width;
  attached_tabstrip_->GetCurrentTabWidths(&sel_width, &unselected_width);
  return gfx::Rect(tab_strip_point.x(), tab_strip_point.y(),
                   static_cast<int>(sel_width),
                   Tab::GetStandardSize().height());
}

gfx::Point TabDragController::GetAttachedDragPoint(
    const gfx::Point& point_in_screen) {
  DCHECK(attached_tabstrip_);  // The tab must be attached.

  gfx::Point tab_loc(point_in_screen);
  views::View::ConvertPointFromScreen(attached_tabstrip_, &tab_loc);
  const int x =
      attached_tabstrip_->GetMirroredXInView(tab_loc.x()) - mouse_offset_.x();

  // TODO: consider caching this.
  std::vector<Tab*> attached_tabs;
  for (size_t i = 0; i < drag_data_.size(); ++i)
    attached_tabs.push_back(drag_data_[i].attached_tab);
  const int size = attached_tabstrip_->GetSizeNeededForTabs(attached_tabs);
  const int max_x = attached_tabstrip_->width() - size;
  return gfx::Point(std::min(std::max(x, 0), max_x), 0);
}

std::vector<Tab*> TabDragController::GetTabsMatchingDraggedContents(
    TabStrip* tabstrip) {
  TabStripModel* model = GetModel(attached_tabstrip_);
  std::vector<Tab*> tabs;
  for (size_t i = 0; i < drag_data_.size(); ++i) {
    int model_index = model->GetIndexOfWebContents(drag_data_[i].contents);
    if (model_index == TabStripModel::kNoTab)
      return std::vector<Tab*>();
    tabs.push_back(tabstrip->tab_at(model_index));
  }
  return tabs;
}

std::vector<gfx::Rect> TabDragController::CalculateBoundsForDraggedTabs() {
  std::vector<gfx::Rect> drag_bounds;
  std::vector<Tab*> attached_tabs;
  for (size_t i = 0; i < drag_data_.size(); ++i)
    attached_tabs.push_back(drag_data_[i].attached_tab);
  attached_tabstrip_->CalculateBoundsForDraggedTabs(attached_tabs,
                                                    &drag_bounds);
  return drag_bounds;
}

void TabDragController::EndDragImpl(EndDragType type) {
  DCHECK(active_);
  active_ = false;

  bring_to_front_timer_.Stop();
  move_stacked_timer_.Stop();

  if (is_dragging_window_) {
    waiting_for_run_loop_to_exit_ = true;

    if (type == NORMAL || (type == TAB_DESTROYED && drag_data_.size() > 1)) {
      SetWindowPositionManaged(GetAttachedBrowserWidget()->GetNativeView(),
                               true);
    }

    // End the nested drag loop.
    GetAttachedBrowserWidget()->EndMoveLoop();
  }

  if (type != TAB_DESTROYED) {
    // We only finish up the drag if we were actually dragging. If start_drag_
    // is false, the user just clicked and released and didn't move the mouse
    // enough to trigger a drag.
    if (started_drag_) {
      RestoreFocus();
      if (type == CANCELED)
        RevertDrag();
      else
        CompleteDrag();
    }
  } else if (drag_data_.size() > 1) {
    initial_selection_model_.Clear();
    RevertDrag();
  }  // else case the only tab we were dragging was deleted. Nothing to do.

  if (!detach_into_browser_)
    ResetDelegates();

  // Clear out drag data so we don't attempt to do anything with it.
  drag_data_.clear();

  TabStrip* owning_tabstrip = (attached_tabstrip_ && detach_into_browser_) ?
      attached_tabstrip_ : source_tabstrip_;
  owning_tabstrip->DestroyDragController();
}

void TabDragController::RevertDrag() {
  std::vector<Tab*> tabs;
  for (size_t i = 0; i < drag_data_.size(); ++i) {
    if (drag_data_[i].contents) {
      // Contents is NULL if a tab was destroyed while the drag was under way.
      tabs.push_back(drag_data_[i].attached_tab);
      RevertDragAt(i);
    }
  }

  bool restore_frame = !detach_into_browser_ &&
                       attached_tabstrip_ != source_tabstrip_;
  if (attached_tabstrip_) {
    if (did_restore_window_)
      MaximizeAttachedWindow();
    if (attached_tabstrip_ == source_tabstrip_) {
      source_tabstrip_->StoppedDraggingTabs(
          tabs, initial_tab_positions_, move_behavior_ == MOVE_VISIBILE_TABS,
          false);
    } else {
      attached_tabstrip_->DraggedTabsDetached();
    }
  }

  if (initial_selection_model_.empty())
    ResetSelection(GetModel(source_tabstrip_));
  else
    GetModel(source_tabstrip_)->SetSelectionFromModel(initial_selection_model_);

  // If we're not attached to any TabStrip, or attached to some other TabStrip,
  // we need to restore the bounds of the original TabStrip's frame, in case
  // it has been hidden.
  if (restore_frame && !restore_bounds_.IsEmpty())
    source_tabstrip_->GetWidget()->SetBounds(restore_bounds_);

  if (detach_into_browser_ && source_tabstrip_)
    source_tabstrip_->GetWidget()->Activate();

  // Return the WebContents to normalcy.  If the tab was attached to a
  // TabStrip before the revert, the decrement has already occurred.
  // If the tab was destroyed, don't attempt to dereference the
  // WebContents pointer.
  if (!detach_into_browser_ && !attached_tabstrip_ && source_dragged_contents())
    source_dragged_contents()->DecrementCapturerCount();
}

void TabDragController::ResetSelection(TabStripModel* model) {
  DCHECK(model);
  ui::ListSelectionModel selection_model;
  bool has_one_valid_tab = false;
  for (size_t i = 0; i < drag_data_.size(); ++i) {
    // |contents| is NULL if a tab was deleted out from under us.
    if (drag_data_[i].contents) {
      int index = model->GetIndexOfWebContents(drag_data_[i].contents);
      DCHECK_NE(-1, index);
      selection_model.AddIndexToSelection(index);
      if (!has_one_valid_tab || i == source_tab_index_) {
        // Reset the active/lead to the first tab. If the source tab is still
        // valid we'll reset these again later on.
        selection_model.set_active(index);
        selection_model.set_anchor(index);
        has_one_valid_tab = true;
      }
    }
  }
  if (!has_one_valid_tab)
    return;

  model->SetSelectionFromModel(selection_model);
}

void TabDragController::RestoreInitialSelection() {
  // First time detaching from the source tabstrip. Reset selection model to
  // initial_selection_model_. Before resetting though we have to remove all
  // the tabs from initial_selection_model_ as it was created with the tabs
  // still there.
  ui::ListSelectionModel selection_model;
  selection_model.Copy(initial_selection_model_);
  for (DragData::const_reverse_iterator i(drag_data_.rbegin());
       i != drag_data_.rend(); ++i) {
    selection_model.DecrementFrom(i->source_model_index);
  }
  // We may have cleared out the selection model. Only reset it if it
  // contains something.
  if (selection_model.empty())
    return;

  // The anchor/active may have been among the tabs that were dragged out. Force
  // the anchor/active to be valid.
  if (selection_model.anchor() == ui::ListSelectionModel::kUnselectedIndex)
    selection_model.set_anchor(selection_model.selected_indices()[0]);
  if (selection_model.active() == ui::ListSelectionModel::kUnselectedIndex)
    selection_model.set_active(selection_model.selected_indices()[0]);
  GetModel(source_tabstrip_)->SetSelectionFromModel(selection_model);
}

void TabDragController::RevertDragAt(size_t drag_index) {
  DCHECK(started_drag_);
  DCHECK(source_tabstrip_);

  base::AutoReset<bool> setter(&is_mutating_, true);
  TabDragData* data = &(drag_data_[drag_index]);
  if (attached_tabstrip_) {
    int index =
        GetModel(attached_tabstrip_)->GetIndexOfWebContents(data->contents);
    if (attached_tabstrip_ != source_tabstrip_) {
      // The Tab was inserted into another TabStrip. We need to put it back
      // into the original one.
      GetModel(attached_tabstrip_)->DetachWebContentsAt(index);
      // TODO(beng): (Cleanup) seems like we should use Attach() for this
      //             somehow.
      GetModel(source_tabstrip_)->InsertWebContentsAt(
          data->source_model_index, data->contents,
          (data->pinned ? TabStripModel::ADD_PINNED : 0));
    } else {
      // The Tab was moved within the TabStrip where the drag was initiated.
      // Move it back to the starting location.
      GetModel(source_tabstrip_)->MoveWebContentsAt(
          index, data->source_model_index, false);
    }
  } else {
    // The Tab was detached from the TabStrip where the drag began, and has not
    // been attached to any other TabStrip. We need to put it back into the
    // source TabStrip.
    GetModel(source_tabstrip_)->InsertWebContentsAt(
        data->source_model_index, data->contents,
        (data->pinned ? TabStripModel::ADD_PINNED : 0));
  }
}

void TabDragController::CompleteDrag() {
  DCHECK(started_drag_);

  if (attached_tabstrip_) {
    if (is_dragging_new_browser_ || did_restore_window_) {
      if (IsDockedOrSnapped(attached_tabstrip_)) {
        was_source_maximized_ = false;
        was_source_fullscreen_ = false;
      }

      // If source window was maximized - maximize the new window as well.
      if (was_source_maximized_ || was_source_fullscreen_)
        MaximizeAttachedWindow();
    }
    attached_tabstrip_->StoppedDraggingTabs(
        GetTabsMatchingDraggedContents(attached_tabstrip_),
        initial_tab_positions_,
        move_behavior_ == MOVE_VISIBILE_TABS,
        true);
  } else {
    // Compel the model to construct a new window for the detached
    // WebContentses.
    views::Widget* widget = source_tabstrip_->GetWidget();
    gfx::Rect window_bounds(widget->GetRestoredBounds());
    window_bounds.set_origin(GetWindowCreatePoint(last_point_in_screen_));

    base::AutoReset<bool> setter(&is_mutating_, true);

    std::vector<TabStripModelDelegate::NewStripContents> contentses;
    for (size_t i = 0; i < drag_data_.size(); ++i) {
      TabStripModelDelegate::NewStripContents item;
      item.web_contents = drag_data_[i].contents;
      item.add_types = drag_data_[i].pinned ? TabStripModel::ADD_PINNED
                                            : TabStripModel::ADD_NONE;
      contentses.push_back(item);
    }

    Browser* new_browser =
        GetModel(source_tabstrip_)->delegate()->CreateNewStripWithContents(
            contentses, window_bounds, widget->IsMaximized());
    ResetSelection(new_browser->tab_strip_model());
    new_browser->window()->Show();

    // Return the WebContents to normalcy.
    if (!detach_into_browser_)
      source_dragged_contents()->DecrementCapturerCount();
  }

  CleanUpHiddenFrame();
}

void TabDragController::MaximizeAttachedWindow() {
  GetAttachedBrowserWidget()->Maximize();
#if defined(USE_ASH)
  if (was_source_fullscreen_ &&
      host_desktop_type_ == chrome::HOST_DESKTOP_TYPE_ASH) {
    // In fullscreen mode it is only possible to get here if the source
    // was in "immersive fullscreen" mode, so toggle it back on.
    ash::accelerators::ToggleFullscreen();
  }
#endif
}

void TabDragController::ResetDelegates() {
  DCHECK(!detach_into_browser_);
  for (size_t i = 0; i < drag_data_.size(); ++i) {
    if (drag_data_[i].contents &&
        drag_data_[i].contents->GetDelegate() == this) {
      drag_data_[i].contents->SetDelegate(
          drag_data_[i].original_delegate);
    }
  }
}

gfx::Rect TabDragController::GetViewScreenBounds(
    views::View* view) const {
  gfx::Point view_topleft;
  views::View::ConvertPointToScreen(view, &view_topleft);
  gfx::Rect view_screen_bounds = view->GetLocalBounds();
  view_screen_bounds.Offset(view_topleft.x(), view_topleft.y());
  return view_screen_bounds;
}

void TabDragController::CleanUpHiddenFrame() {
  // If the model we started dragging from is now empty, we must ask the
  // delegate to close the frame.
  if (!detach_into_browser_ && GetModel(source_tabstrip_)->empty())
    GetModel(source_tabstrip_)->delegate()->CloseFrameAfterDragSession();
}

void TabDragController::BringWindowUnderPointToFront(
    const gfx::Point& point_in_screen) {
  aura::Window* window = GetLocalProcessWindow(point_in_screen, true);

  // Only bring browser windows to front - only windows with a TabStrip can
  // be tab drag targets.
  if (!GetTabStripForWindow(window))
    return;

  if (window) {
    views::Widget* widget_window = views::Widget::GetWidgetForNativeView(
        window);
    if (!widget_window)
      return;

#if defined(USE_ASH)
    if (host_desktop_type_ == chrome::HOST_DESKTOP_TYPE_ASH) {
      // TODO(varkha): The code below ensures that the phantom drag widget
      // is shown on top of browser windows. The code should be moved to ash/
      // and the phantom should be able to assert its top-most state on its own.
      // One strategy would be for DragWindowController to
      // be able to observe stacking changes to the phantom drag widget's
      // siblings in order to keep it on top. One way is to implement a
      // notification that is sent to a window parent's observers when a
      // stacking order is changed among the children of that same parent.
      // Note that OnWindowStackingChanged is sent only to the child that is the
      // argument of one of the Window::StackChildX calls and not to all its
      // siblings affected by the stacking change.
      aura::Window* browser_window = widget_window->GetNativeView();
      // Find a topmost non-popup window and stack the recipient browser above
      // it in order to avoid stacking the browser window on top of the phantom
      // drag widget created by DragWindowController in a second display.
      for (aura::Window::Windows::const_reverse_iterator it =
           browser_window->parent()->children().rbegin();
           it != browser_window->parent()->children().rend(); ++it) {
        // If the iteration reached the recipient browser window then it is
        // already topmost and it is safe to return with no stacking change.
        if (*it == browser_window)
          return;
        if ((*it)->type() != ui::wm::WINDOW_TYPE_POPUP) {
          widget_window->StackAbove(*it);
          break;
        }
      }
    } else {
      widget_window->StackAtTop();
    }
#else
    widget_window->StackAtTop();
#endif

    // The previous call made the window appear on top of the dragged window,
    // move the dragged window to the front.
    if (is_dragging_window_)
      attached_tabstrip_->GetWidget()->StackAtTop();
  }
}

TabStripModel* TabDragController::GetModel(
    TabStrip* tabstrip) const {
  return static_cast<BrowserTabStripController*>(tabstrip->controller())->
      model();
}

views::Widget* TabDragController::GetAttachedBrowserWidget() {
  return attached_tabstrip_->GetWidget();
}

bool TabDragController::AreTabsConsecutive() {
  for (size_t i = 1; i < drag_data_.size(); ++i) {
    if (drag_data_[i - 1].source_model_index + 1 !=
        drag_data_[i].source_model_index) {
      return false;
    }
  }
  return true;
}

gfx::Rect TabDragController::CalculateDraggedBrowserBounds(
    TabStrip* source,
    const gfx::Point& point_in_screen,
    std::vector<gfx::Rect>* drag_bounds) {
  gfx::Point center(0, source->height() / 2);
  views::View::ConvertPointToWidget(source, &center);
  gfx::Rect new_bounds(source->GetWidget()->GetRestoredBounds());
  if (source->GetWidget()->IsMaximized()) {
    // If the restore bounds is really small, we don't want to honor it
    // (dragging a really small window looks wrong), instead make sure the new
    // window is at least 50% the size of the old.
    const gfx::Size max_size(
        source->GetWidget()->GetWindowBoundsInScreen().size());
    new_bounds.set_width(
        std::max(max_size.width() / 2, new_bounds.width()));
    new_bounds.set_height(
        std::max(max_size.height() / 2, new_bounds.height()));
  }
  new_bounds.set_y(point_in_screen.y() - center.y());
  switch (GetDetachPosition(point_in_screen)) {
    case DETACH_BEFORE:
      new_bounds.set_x(point_in_screen.x() - center.x());
      new_bounds.Offset(-mouse_offset_.x(), 0);
      break;
    case DETACH_AFTER: {
      gfx::Point right_edge(source->width(), 0);
      views::View::ConvertPointToWidget(source, &right_edge);
      new_bounds.set_x(point_in_screen.x() - right_edge.x());
      new_bounds.Offset(drag_bounds->back().right() - mouse_offset_.x(), 0);
      OffsetX(-(*drag_bounds)[0].x(), drag_bounds);
      break;
    }
    default:
      break; // Nothing to do for DETACH_ABOVE_OR_BELOW.
  }

  // To account for the extra vertical on restored windows that is absent on
  // maximized windows, add an additional vertical offset extracted from the tab
  // strip.
  if (source->GetWidget()->IsMaximized())
    new_bounds.Offset(0, -source->button_v_offset());
  return new_bounds;
}

void TabDragController::AdjustBrowserAndTabBoundsForDrag(
    int last_tabstrip_width,
    const gfx::Point& point_in_screen,
    std::vector<gfx::Rect>* drag_bounds) {
  attached_tabstrip_->InvalidateLayout();
  attached_tabstrip_->DoLayout();
  const int dragged_tabstrip_width = attached_tabstrip_->tab_area_width();

  // If the new tabstrip is smaller than the old resize the tabs.
  if (dragged_tabstrip_width < last_tabstrip_width) {
    const float leading_ratio =
        drag_bounds->front().x() / static_cast<float>(last_tabstrip_width);
    *drag_bounds = CalculateBoundsForDraggedTabs();

    if (drag_bounds->back().right() < dragged_tabstrip_width) {
      const int delta_x =
          std::min(static_cast<int>(leading_ratio * dragged_tabstrip_width),
                   dragged_tabstrip_width -
                       (drag_bounds->back().right() -
                        drag_bounds->front().x()));
      OffsetX(delta_x, drag_bounds);
    }

    // Reposition the restored window such that the tab that was dragged remains
    // under the mouse cursor.
    gfx::Point offset(
        static_cast<int>((*drag_bounds)[source_tab_index_].width() *
                         offset_to_width_ratio_) +
        (*drag_bounds)[source_tab_index_].x(), 0);
    views::View::ConvertPointToWidget(attached_tabstrip_, &offset);
    gfx::Rect bounds = GetAttachedBrowserWidget()->GetWindowBoundsInScreen();
    bounds.set_x(point_in_screen.x() - offset.x());
    GetAttachedBrowserWidget()->SetBounds(bounds);
  }
  attached_tabstrip_->SetTabBoundsForDrag(*drag_bounds);
}

Browser* TabDragController::CreateBrowserForDrag(
    TabStrip* source,
    const gfx::Point& point_in_screen,
    gfx::Vector2d* drag_offset,
    std::vector<gfx::Rect>* drag_bounds) {
  gfx::Rect new_bounds(CalculateDraggedBrowserBounds(source,
                                                     point_in_screen,
                                                     drag_bounds));
  *drag_offset = point_in_screen - new_bounds.origin();

  Profile* profile =
      Profile::FromBrowserContext(drag_data_[0].contents->GetBrowserContext());
  Browser::CreateParams create_params(Browser::TYPE_TABBED,
                                      profile,
                                      host_desktop_type_);
  create_params.initial_bounds = new_bounds;
  Browser* browser = new Browser(create_params);
  is_dragging_new_browser_ = true;
  SetWindowPositionManaged(browser->window()->GetNativeWindow(), false);
  // If the window is created maximized then the bounds we supplied are ignored.
  // We need to reset them again so they are honored.
  browser->window()->SetBounds(new_bounds);

  return browser;
}

gfx::Point TabDragController::GetCursorScreenPoint() {
#if defined(USE_ASH)
  if (host_desktop_type_ == chrome::HOST_DESKTOP_TYPE_ASH &&
      event_source_ == EVENT_SOURCE_TOUCH &&
      aura::Env::GetInstance()->is_touch_down()) {
    views::Widget* widget = GetAttachedBrowserWidget();
    DCHECK(widget);
    aura::Window* widget_window = widget->GetNativeWindow();
    DCHECK(widget_window->GetRootWindow());
    gfx::PointF touch_point_f;
    bool got_touch_point = ui::GestureRecognizer::Get()->
        GetLastTouchPointForTarget(widget_window, &touch_point_f);
    // TODO(tdresser): Switch to using gfx::PointF. See crbug.com/337824.
    gfx::Point touch_point = gfx::ToFlooredPoint(touch_point_f);
    DCHECK(got_touch_point);
    ash::wm::ConvertPointToScreen(widget_window->GetRootWindow(), &touch_point);
    return touch_point;
  }
#endif
  return screen_->GetCursorScreenPoint();
}

gfx::Vector2d TabDragController::GetWindowOffset(
    const gfx::Point& point_in_screen) {
  TabStrip* owning_tabstrip = (attached_tabstrip_ && detach_into_browser_) ?
      attached_tabstrip_ : source_tabstrip_;
  views::View* toplevel_view = owning_tabstrip->GetWidget()->GetContentsView();

  gfx::Point point = point_in_screen;
  views::View::ConvertPointFromScreen(toplevel_view, &point);
  return point.OffsetFromOrigin();
}

gfx::NativeWindow TabDragController::GetLocalProcessWindow(
    const gfx::Point& screen_point,
    bool exclude_dragged_view) {
  std::set<aura::Window*> exclude;
  if (exclude_dragged_view) {
    aura::Window* dragged_window =
        attached_tabstrip_->GetWidget()->GetNativeView();
    if (dragged_window)
      exclude.insert(dragged_window);
  }
#if defined(OS_LINUX) && !defined(OS_CHROMEOS)
  // Exclude windows which are pending deletion via Browser::TabStripEmpty().
  // These windows can be returned in the Linux Aura port because the browser
  // window which was used for dragging is not hidden once all of its tabs are
  // attached to another browser window in DragBrowserToNewTabStrip().
  // TODO(pkotwicz): Fix this properly (crbug.com/358482)
  BrowserList* browser_list = BrowserList::GetInstance(
      chrome::HOST_DESKTOP_TYPE_NATIVE);
  for (BrowserList::const_iterator it = browser_list->begin();
       it != browser_list->end(); ++it) {
    if ((*it)->tab_strip_model()->empty())
      exclude.insert((*it)->window()->GetNativeWindow());
  }
#endif
  return GetLocalProcessWindowAtPoint(host_desktop_type_,
                                      screen_point,
                                      exclude);

}
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root/chrome/browser/ui/views/tabs/tab_drag_controller.cc

DEFINITIONS
