Remove --ash-disable-overview-mode

ash/shell.cc

Index: ash/shell.cc
diff --git a/ash/shell.cc b/ash/shell.cc
index f0f59bd9a234e047a5b0e587a2aa577bcf20ce92..e5857c0f031697632ebb4b2f27ead60f3a897a3b 100644
--- a/ash/shell.cc
+++ b/ash/shell.cc
@@ -75,7 +75,6 @@
 #include "ash/wm/user_activity_detector.h"
 #include "ash/wm/video_detector.h"
 #include "ash/wm/window_animations.h"
-#include "ash/wm/window_cycle_controller.h"
 #include "ash/wm/window_positioner.h"
 #include "ash/wm/window_properties.h"
 #include "ash/wm/window_util.h"
@@ -693,7 +692,6 @@ Shell::~Shell() {
   resize_shadow_controller_.reset();
 
   window_selector_controller_.reset();
-  window_cycle_controller_.reset();
   mru_window_tracker_.reset();
 
   // |shelf_window_watcher_| has a weak pointer to |shelf_Model_|
@@ -926,7 +924,6 @@ void Shell::Init() {
 
   high_contrast_controller_.reset(new HighContrastController);
   video_detector_.reset(new VideoDetector);
-  window_cycle_controller_.reset(new WindowCycleController());
   window_selector_controller_.reset(new WindowSelectorController());
 
   tooltip_controller_.reset(
@@ -1038,7 +1035,6 @@ void Shell::InitRootWindow(aura::Window* root_window) {
   DCHECK(activation_client_);
   DCHECK(visibility_controller_.get());
   DCHECK(drag_drop_controller_.get());
-  DCHECK(window_cycle_controller_.get());
 
   aura::client::SetFocusClient(root_window, focus_client_.get());
   input_method_filter_->SetInputMethodPropertyInRootWindow(root_window);