Delegate root layer scroll offset to android_webview.

content/renderer/android/synchronous_compositor_impl.h

 // Copyright 2013 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_RENDERER_ANDROID_SYNCHRONOUS_COMPOSITOR_IMPL_H_
 #define CONTENT_RENDERER_ANDROID_SYNCHRONOUS_COMPOSITOR_IMPL_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 #include "cc/input/layer_scroll_offset_delegate.h"
 #include "content/public/renderer/android/synchronous_compositor.h"
 #include "content/renderer/android/synchronous_compositor_output_surface.h"
 
 namespace cc {
 class OutputSurface;
 }
 
 namespace content {
 
 // The purpose of this class is to act as the intermediary between the various
 // components that make up the 'synchronous compositor mode' implementation and
 // expose their functionality via the SynchronousCompositor interface.
 // This class is created on the main thread but most of the APIs are called
 // from the Compositor thread.
 class SynchronousCompositorImpl
     : public SynchronousCompositor,
-      public SynchronousCompositorOutputSurfaceDelegate {
+      public SynchronousCompositorOutputSurfaceDelegate,
+      public cc::LayerScrollOffsetDelegate {
  public:
   explicit SynchronousCompositorImpl(int32 routing_id);
   virtual ~SynchronousCompositorImpl();
 
   scoped_ptr<cc::OutputSurface> CreateOutputSurface();
 
   // SynchronousCompositor
   virtual bool IsHwReady() OVERRIDE;
   virtual void SetClient(SynchronousCompositorClient* compositor_client)
       OVERRIDE;
   virtual bool DemandDrawSw(SkCanvas* canvas) OVERRIDE;
   virtual bool DemandDrawHw(
       gfx::Size view_size,
       const gfx::Transform& transform,
       gfx::Rect clip) OVERRIDE;
 
   // SynchronousCompositorOutputSurfaceDelegate
   virtual void SetContinuousInvalidate(bool enable) OVERRIDE;
   virtual void DidCreateSynchronousOutputSurface() OVERRIDE;
   virtual void DidDestroySynchronousOutputSurface() OVERRIDE;
 
+  // LayerScrollOffsetDelegate
+  virtual void SetTotalScrollOffset(gfx::Vector2dF new_value) OVERRIDE;
+  virtual gfx::Vector2dF GetTotalScrollOffset() OVERRIDE;
+
  private:
   bool CalledOnValidThread() const;
 
   int routing_id_;
   SynchronousCompositorClient* compositor_client_;
   SynchronousCompositorOutputSurface* output_surface_;
 
   DISALLOW_COPY_AND_ASSIGN(SynchronousCompositorImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_ANDROID_SYNCHRONOUS_COMPOSITOR_IMPL_H_