Added arrow key navigation to 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 "ui/views/controls/button/button.h"
 
 namespace ash {
 
 // Transparent window that covers window selector items and handles mouse and
 // gestures on overview mode for them.
 class TransparentActivateWindowButton : public views::ButtonListener {
  public:
   explicit TransparentActivateWindowButton(aura::Window* activate_window);
   virtual ~TransparentActivateWindowButton();
 
   // Sets the bounds of the transparent window.
   void SetBounds(const gfx::Rect& bounds);
 
+  // Sends an a11y focus alert so that if chromevox is enabled, the window title
+  // is read.
+  void SendFocusAlert() const;
+
   // views::ButtonListener:
   virtual void ButtonPressed(views::Button* sender,
                              const ui::Event& event) OVERRIDE;
 
  private:
   // The transparent window event handler widget itself.
   scoped_ptr<views::Widget> event_handler_widget_;
 
   // Pointer to the window that the button activates.
   aura::Window* activate_window_;
 
   DISALLOW_COPY_AND_ASSIGN(TransparentActivateWindowButton);
 };
 
 }  // namespace ash
 
 #endif  // ASH_WM_OVERVIEW_TRANSPARENT_ACTIVATE_WINDOW_BUTTON_H_