Smooth Tab Switching on aura.

content/browser/renderer_host/render_widget_host_view_aura.h

 // 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.
 
 #ifndef CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_AURA_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_AURA_H_
 #pragma once
 
 #include <map>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/memory/linked_ptr.h"
 #include "base/memory/ref_counted.h"
 #include "content/browser/renderer_host/image_transport_factory.h"
 #include "content/browser/renderer_host/render_widget_host_view_base.h"
 #include "content/common/content_export.h"
 #include "ui/aura/client/activation_delegate.h"
 #include "ui/aura/window_delegate.h"
 #include "ui/base/ime/text_input_client.h"
 #include "ui/compositor/compositor_observer.h"
 #include "ui/gfx/rect.h"
 #include "webkit/glue/webcursor.h"
 
+namespace aura {
+class CompositorLock;
+}
+
 namespace content {
 class RenderWidgetHostImpl;
 class RenderWidgetHostView;
 }
 
 namespace gfx {
 class Canvas;
 }
 
 namespace ui {
@@ skipping 265 matching lines @@
   bool needs_update_texture_;
 
   // Used to prevent further resizes while a resize is pending.
   class ResizeLock;
   // These locks are the ones waiting for a texture of the right size to come
   // back from the renderer/GPU process.
   std::vector<linked_ptr<ResizeLock> > resize_locks_;
   // These locks are the ones waiting for a frame to be drawn.
   std::vector<linked_ptr<ResizeLock> > locks_pending_draw_;
 
+  // This lock is for waiting for a front surface to become available to draw.
+  scoped_refptr<aura::CompositorLock> released_front_lock_;
+
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewAura);
 };
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_AURA_H_