Add window overview mode behind --ash-enable-overview-mode flag to F5 key.

ash/shell_delegate.h

 // 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.
 
 #ifndef ASH_SHELL_DELEGATE_H_
 #define ASH_SHELL_DELEGATE_H_
 
 #include <string>
 
 #include "ash/ash_export.h"
@@ skipping 42 matching lines @@
   UMA_ACCEL_KEYBOARD_BRIGHTNESS_DOWN_F6,
   UMA_ACCEL_KEYBOARD_BRIGHTNESS_UP_F7,
   UMA_ACCEL_LOCK_SCREEN_L,
   UMA_ACCEL_LOCK_SCREEN_LOCK_BUTTON,
   UMA_ACCEL_LOCK_SCREEN_POWER_BUTTON,
   UMA_ACCEL_FULLSCREEN_F4,
   UMA_ACCEL_MAXIMIZE_RESTORE_F4,
   UMA_ACCEL_NEWTAB_T,
   UMA_ACCEL_NEXTWINDOW_F5,
   UMA_ACCEL_NEXTWINDOW_TAB,
+  UMA_ACCEL_OVERVIEW_F5,
   UMA_ACCEL_PREVWINDOW_F5,
   UMA_ACCEL_PREVWINDOW_TAB,
   UMA_ACCEL_EXIT_FIRST_Q,
   UMA_ACCEL_EXIT_SECOND_Q,
   UMA_ACCEL_SEARCH_LWIN,
   UMA_ACCEL_SHUT_DOWN_POWER_BUTTON,
   UMA_CLOSE_THROUGH_CONTEXT_MENU,
   UMA_LAUNCHER_CLICK_ON_APP,
   UMA_LAUNCHER_CLICK_ON_APPLIST_BUTTON,
   UMA_MINIMIZE_PER_KEY,
@@ skipping 183 matching lines @@
   // value.
   virtual RootWindowHostFactory* CreateRootWindowHostFactory() = 0;
 
   // Get the product name.
   virtual base::string16 GetProductName() const = 0;
 };
 
 }  // namespace ash
 
 #endif  // ASH_SHELL_DELEGATE_H_