Remove --ash-disable-overview-mode

ash/ash_switches.h

Index: ash/ash_switches.h
diff --git a/ash/ash_switches.h b/ash/ash_switches.h
index 93e86aab563bff00544d0f67750e294ccdc9cc14..0e14fdc2999fbd52d6469100a7a0f1d935313269 100644
--- a/ash/ash_switches.h
+++ b/ash/ash_switches.h
@@ -33,7 +33,6 @@ ASH_EXPORT extern const char kAshDisableAudioDeviceMenu[];
 ASH_EXPORT extern const char kAshDisableDockedWindows[];
 ASH_EXPORT extern const char kAshDisableDragAndDropAppListToLauncher[];
 ASH_EXPORT extern const char kAshDisableDragOffShelf[];
-ASH_EXPORT extern const char kAshDisableOverviewMode[];
 #if defined(OS_CHROMEOS)
 ASH_EXPORT extern const char kAshDisableUsbChargerNotification[];
 ASH_EXPORT extern const char kAshEnableAudioDeviceMenu[];
@@ -86,9 +85,6 @@ ASH_EXPORT bool UseImmersiveFullscreenForAllWindows();
 // Returns true if multiple user icons are allowed in the tray.
 ASH_EXPORT bool UseMultiUserTray();
 
-// Returns true if overview mode should be activated for window switching.
-ASH_EXPORT bool UseOverviewMode();
-
 // Returns true if docked windows feature is enabled.
 ASH_EXPORT bool UseDockedWindows();