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

ash/ash_switches.cc

 // 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 "ash/ash_switches.h"
 
 #include "base/command_line.h"
 
 namespace ash {
 namespace switches {
@@ skipping 108 matching lines @@
 #if defined(OS_CHROMEOS)
 // TODO(jamescook): Remove this unused flag. It exists only to allow the
 // "Enable new audio handler" about:flags item to have the tri-state
 // default/enabled/disabled UI.
 const char kAshEnableNewAudioHandler[] = "ash-enable-new-audio-handler";
 #endif
 
 // Enables the Oak tree viewer.
 const char kAshEnableOak[] = "ash-enable-oak";
 
+// Enables overview mode for window switching.
+const char kAshEnableOverviewMode[] = "ash-enable-overview-mode";
+
 // Enables "sticky" edges instead of "snap-to-edge"
 const char kAshEnableStickyEdges[] = "ash-enable-sticky-edges";
 
 // Enables showing the tray bubble by dragging on the shelf.
 const char kAshEnableTrayDragging[] = "ash-enable-tray-dragging";
 
 // Forces chrome to use mirror mode when an external display is connected.
 const char kAshForceMirrorMode[] = "ash-force-mirror-mode";
 
 // Hides notifications that are irrelevant to Chrome OS device factory testing,
@@ skipping 73 matching lines @@
 }
 
 bool UseUsbChargerNotification() {
   return !CommandLine::ForCurrentProcess()->
         HasSwitch(ash::switches::kAshDisableUsbChargerNotification);
 }
 #endif
 
 }  // namespace switches
 }  // namespace ash