Add compile flag for enabling the compostior

sky/viewer/platform/weblayertreeview_impl.h

 // Copyright 2014 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 SKY_VIEWER_PLATFORM_WEBLAYERTREEVIEW_IMPL_H_
 #define SKY_VIEWER_PLATFORM_WEBLAYERTREEVIEW_IMPL_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/single_thread_task_runner.h"
+#include "cc/layers/content_layer.h"
+#include "cc/layers/content_layer_client.h"
 #include "cc/trees/layer_tree_host_client.h"
 #include "mojo/cc/output_surface_mojo.h"
 #include "mojo/services/public/interfaces/gpu/gpu.mojom.h"
 #include "mojo/services/public/interfaces/surfaces/surfaces_service.mojom.h"
 #include "sky/engine/public/platform/WebLayerTreeView.h"
 
 namespace base {
 class MessageLoopProxy;
 }
 
 namespace blink {
 class WebWidget;
 }
 
 namespace cc {
 class LayerTreeHost;
 }
 
 namespace mojo {
 class View;
 }
 
 namespace sky {
 
 class WebLayerTreeViewImpl : public blink::WebLayerTreeView,
                              public cc::LayerTreeHostClient,
+                             public cc::ContentLayerClient,
                              public mojo::OutputSurfaceMojoClient {
  public:
   WebLayerTreeViewImpl(
       scoped_refptr<base::MessageLoopProxy> compositor_message_loop_proxy,
       mojo::SurfacesServicePtr surfaces_service,
       mojo::GpuPtr gpu_service);
   virtual ~WebLayerTreeViewImpl();
 
-  void set_widget(blink::WebWidget* widget) { widget_ = widget; }
+  void set_widget(blink::WebWidget* widget);
   void set_view(mojo::View* view) { view_ = view; }
 
   // cc::LayerTreeHostClient implementation.
   virtual void WillBeginMainFrame(int frame_id) override;
   virtual void DidBeginMainFrame() override;
   virtual void BeginMainFrame(const cc::BeginFrameArgs& args) override;
   virtual void Layout() override;
   virtual void ApplyViewportDeltas(const gfx::Vector2d& scroll_delta,
                                    float page_scale,
                                    float top_controls_delta) override;
   virtual void ApplyViewportDeltas(const gfx::Vector2d& inner_delta,
                                    const gfx::Vector2d& outer_delta,
                                    float page_scale,
                                    float top_controls_delta) override;
   virtual void RequestNewOutputSurface(bool fallback) override;
   virtual void DidInitializeOutputSurface() override;
   virtual void WillCommit() override;
   virtual void DidCommit() override;
   virtual void DidCommitAndDrawFrame() override;
   virtual void DidCompleteSwapBuffers() override;
   virtual void RateLimitSharedMainThreadContext() override {}
 
+  // cc::ContentLayerClient
+  void PaintContents(SkCanvas* canvas,
+                     const gfx::Rect& clip,
+                     GraphicsContextStatus gc_status) override;
+  bool FillsBoundsCompletely() const override;
+
   // blink::WebLayerTreeView implementation.
   virtual void setSurfaceReady() override;
   virtual void setRootLayer(const blink::WebLayer& layer) override;
   virtual void clearRootLayer() override;
   virtual void setViewportSize(
       const blink::WebSize& device_viewport_size) override;
   virtual blink::WebSize deviceViewportSize() const override;
   virtual void setDeviceScaleFactor(float) override;
   virtual float deviceScaleFactor() const override;
   virtual void setBackgroundColor(blink::WebColor color) override;
@@ skipping 36 matching lines @@
   blink::WebWidget* widget_;
   mojo::View* view_;
   scoped_ptr<cc::LayerTreeHost> layer_tree_host_;
   mojo::SurfacesServicePtr surfaces_service_;
   scoped_ptr<cc::OutputSurface> output_surface_;
   mojo::GpuPtr gpu_service_;
   scoped_refptr<base::SingleThreadTaskRunner>
       main_thread_compositor_task_runner_;
   base::WeakPtr<WebLayerTreeViewImpl> main_thread_bound_weak_ptr_;
 
+  scoped_refptr<cc::ContentLayer> root_layer_;
+
   base::WeakPtrFactory<WebLayerTreeViewImpl> weak_factory_;
   DISALLOW_COPY_AND_ASSIGN(WebLayerTreeViewImpl);
 };
 
 }  // namespace sky
 
 #endif  // SKY_VIEWER_PLATFORM_WEBLAYERTREEVIEW_IMPL_H_