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

ash/ash_switches.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_ASH_SWITCHES_H_
 #define ASH_ASH_SWITCHES_H_
 
 #include "ash/ash_export.h"
 
 #include "build/build_config.h"
@@ skipping 35 matching lines @@
 ASH_EXPORT extern const char kAshDisableUsbChargerNotification[];
 #endif
 ASH_EXPORT extern const char kAshEnableAdvancedGestures[];
 ASH_EXPORT extern const char kAshEnableBrightnessControl[];
 ASH_EXPORT extern const char kAshEnableDockedWindows[];
 #if defined(OS_LINUX)
 ASH_EXPORT extern const char kAshEnableMemoryMonitor[];
 #endif
 ASH_EXPORT extern const char kAshEnableImmersiveFullscreen[];
 ASH_EXPORT extern const char kAshEnableOak[];
+ASH_EXPORT extern const char kAshEnableOverviewMode[];
 ASH_EXPORT extern const char kAshEnableStickyEdges[];
 ASH_EXPORT extern const char kAshEnableTrayDragging[];
 ASH_EXPORT extern const char kAshEnableWorkspaceScrubbing[];
 ASH_EXPORT extern const char kAshForceMirrorMode[];
 ASH_EXPORT extern const char kAshHideNotificationsForFactory[];
 ASH_EXPORT extern const char kAshHostWindowBounds[];
 ASH_EXPORT extern const char kAshImmersiveHideTabIndicators[];
 ASH_EXPORT extern const char kAshSecondaryDisplayLayout[];
 ASH_EXPORT extern const char kAshTouchHud[];
 ASH_EXPORT extern const char kAshUseAlternateShelfLayout[];
@@ skipping 16 matching lines @@
 
 // Returns true if a notification should appear when a low-power USB charger
 // is connected.
 ASH_EXPORT bool UseUsbChargerNotification();
 #endif
 
 }  // namespace switches
 }  // namespace ash
 
 #endif  // ASH_ASH_SWITCHES_H_