Remove --ash-disable-overview-mode

ash/ash_switches.cc

Index: ash/ash_switches.cc
diff --git a/ash/ash_switches.cc b/ash/ash_switches.cc
index e3ca863731ff885dff7a4cc14cc456d016671df7..a558296225c1fb4b44e3c81694fe46f981f4a294 100644
--- a/ash/ash_switches.cc
+++ b/ash/ash_switches.cc
@@ -68,9 +68,6 @@ const char kAshDisableDragAndDropAppListToLauncher[] =
 // Disable dragging items off the shelf to unpin them.
 const char kAshDisableDragOffShelf[] = "ash-disable-drag-off-shelf";
 
-// Disables overview mode for window switching.
-const char kAshDisableOverviewMode[] = "ash-disable-overview-mode";
-
 #if defined(OS_CHROMEOS)
 // Disable the notification when a low-power USB charger is connected.
 const char kAshDisableUsbChargerNotification[] =
@@ -217,10 +214,6 @@ bool UseMultiUserTray() {
 #endif
 }
 
-bool UseOverviewMode() {
-  return !CommandLine::ForCurrentProcess()->HasSwitch(kAshDisableOverviewMode);
-}
-
 bool UseDockedWindows() {
   return !CommandLine::ForCurrentProcess()->HasSwitch(kAshDisableDockedWindows);
 }