Adding a gray semi transparent backdrop behind the topmost window within the default container

ash/wm/workspace_controller.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/wm/workspace_controller.h"
 
 #include "ash/root_window_controller.h"
 #include "ash/shelf/shelf_layout_manager.h"
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
 #include "ash/wm/window_animations.h"
 #include "ash/wm/window_state.h"
 #include "ash/wm/window_util.h"
 #include "ash/wm/workspace/workspace_event_handler.h"
 #include "ash/wm/workspace/workspace_layout_manager.h"
+#include "ash/wm/workspace/workspace_layout_manager_delegate.h"
 #include "ui/aura/client/activation_client.h"
 #include "ui/aura/client/aura_constants.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_event_dispatcher.h"
 #include "ui/compositor/layer.h"
 #include "ui/compositor/scoped_layer_animation_settings.h"
 #include "ui/views/corewm/visibility_controller.h"
 #include "ui/views/corewm/window_animations.h"
 
 namespace ash {
@@ skipping 102 matching lines @@
             ui::LayerAnimationElement::BRIGHTNESS |
             ui::LayerAnimationElement::VISIBILITY);
     settings.SetTweenType(gfx::Tween::EASE_OUT);
     settings.SetTransitionDuration(
         base::TimeDelta::FromMilliseconds(kCrossFadeDurationMS));
     viewport_->layer()->SetTransform(gfx::Transform());
     viewport_->layer()->SetOpacity(1.0f);
   }
 }
 
+void WorkspaceController::SetMaximizeBackdropDelegate(
+    scoped_ptr<WorkspaceLayoutManagerDelegate> delegate) {
+  layout_manager_->SetMaximizeBackdropDelegate(delegate.Pass());
+}
+
 }  // namespace internal
 }  // namespace ash