aura: Add Ctrl-Shift-Q for quit and Ctrl-Shift-L for lock in chromeos.

ash/app_list/app_list.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/app_list/app_list.h"
 
 #include "ash/app_list/app_list_model.h"
 #include "ash/app_list/app_list_view.h"
 #include "ash/ash_switches.h"
 #include "ash/shell_delegate.h"
@@ skipping 102 matching lines @@
   Shell::GetInstance()->RemoveRootWindowEventFilter(this);
   widget_ = NULL;
 }
 
 void AppList::ScheduleAnimation() {
   ui::Layer* layer = GetLayer(widget_);
   ui::ScopedLayerAnimationSettings app_list_animation(layer->GetAnimator());
   layer->SetBounds(GetPreferredBounds(is_visible_));
   layer->SetOpacity(is_visible_ ? 1.0 : 0.0);
 
-  ui::Layer* default_container_layer = Shell::GetInstance()->GetContainer(
-      internal::kShellWindowId_DefaultContainer)->layer();
+  aura::Window* default_container = Shell::GetInstance()->GetContainer(
+      internal::kShellWindowId_DefaultContainer);
+  if (!default_container)
+    return;
+  ui::Layer* default_container_layer = default_container->layer();
   ui::ScopedLayerAnimationSettings default_container_animation(
       default_container_layer->GetAnimator());
   default_container_layer->SetOpacity(is_visible_ ? 0.0 : 1.0);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // AppList, aura::EventFilter implementation:
 
 bool AppList::PreHandleKeyEvent(aura::Window* target,
                                 aura::KeyEvent* event) {
@@ skipping 49 matching lines @@
 }
 
 void AppList::OnWidgetActivationChanged(views::Widget* widget, bool active) {
   DCHECK(widget_ == widget);
   if (widget_ && is_visible_ && !active)
     SetVisible(false);
 }
 
 }  // namespace internal
 }  // namespace ash