Implemented swipe to close in overview mode.

ash/wm/overview/transparent_activate_window_button.h

 // Copyright 2014 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.
 
 #ifndef ASH_WM_OVERVIEW_TRANSPARENT_ACTIVATE_WINDOW_BUTTON_H_
 #define ASH_WM_OVERVIEW_TRANSPARENT_ACTIVATE_WINDOW_BUTTON_H_
 
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/strings/string16.h"
 #include "ui/gfx/geometry/rect.h"
 
 namespace aura {
 class Window;
 }  // namespace aura
 
 namespace views {
 class Button;
 class Widget;
 }  // namespace views
 
 namespace ash {
-
+class TransparentButton;
 class TransparentActivateWindowButtonDelegate;
 
 // Transparent window that covers window selector items and handles mouse and
 // gestures on overview mode for them.
 class TransparentActivateWindowButton {
  public:
   TransparentActivateWindowButton(
       aura::Window* root_window,
       TransparentActivateWindowButtonDelegate* delegate);
   ~TransparentActivateWindowButton();
 
   // Sets the accessibility name.
   void SetAccessibleName(const base::string16& name);
 
   // Sets the bounds of the transparent window.
   void SetBounds(const gfx::Rect& bounds);
 
+  // Set the distance, in pixels, for which a drag gesture will cause a window
+  // to be closed when the drag distance exceeds |distance|.
+  void SetCloseWindowDistanceMinimum(int distance);
+
   // Sends an accessibility focus alert so that if chromevox is enabled, the
   // window title is read.
   void SendFocusAlert() const;
 
   // Stacks |this| above |activate_button| in the window z-ordering.
   void StackAbove(TransparentActivateWindowButton* activate_button);
 
  private:
   // The transparent window event handler widget itself.
   scoped_ptr<views::Widget> event_handler_widget_;
 
   // The transparent button view that handles user input. Not owned.
-  views::Button* transparent_button_;
+  TransparentButton* transparent_button_;
 
   DISALLOW_COPY_AND_ASSIGN(TransparentActivateWindowButton);
 };
 
 }  // namespace ash
 
 #endif  // ASH_WM_OVERVIEW_TRANSPARENT_ACTIVATE_WINDOW_BUTTON_H_