Delegate root layer scroll offset to android_webview.

content/renderer/android/synchronous_compositor_output_surface.h

 // Copyright (c) 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_OUTPUT_SURFACE_H_
-#define CONTENT_RENDERER_ANDOIRD_SYNCHRONOUS_COMPOSITOR_OUTPUT_SURFACE_H_
+#define CONTENT_RENDERER_ANDROID_SYNCHRONOUS_COMPOSITOR_OUTPUT_SURFACE_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
 #include "cc/output/output_surface.h"
 #include "content/public/renderer/android/synchronous_compositor.h"
 
 namespace content {
 
 class SynchronousCompositorClient;
 class WebGraphicsContext3DCommandBufferImpl;
 
 // Specialization of the output surface that adapts it to implement the
 // content::SynchronousCompositor public API. This class effects an "inversion
 // of control" - enabling drawing to be  orchestrated by the embedding
 // layer, instead of driven by the compositor internals - hence it holds two
 // 'client' pointers (including |client_| in the OutputSurface baseclass) which
 // represent the consumers of the two roles in plays.
 // This class can be created only on the main thread, but then becomes pinned
 // to a fixed thread when BindToClient is called.
 class SynchronousCompositorOutputSurface
-    : NON_EXPORTED_BASE(public cc::OutputSurface),
-      NON_EXPORTED_BASE(public SynchronousCompositor) {
+    : NON_EXPORTED_BASE(public cc::OutputSurface) {
  public:
-  explicit SynchronousCompositorOutputSurface(int32 routing_id);
+  class Delegate {

[joth, 2013/05/16 18:21:42]

the emerging preference is not to do inner classes - I don't have strong opinion
on that though

+   public:
+    virtual void SetContinuousInvalidate(bool enable) = 0;
+    virtual void DidCreateSynchronousCompositor() = 0;
+    virtual void DidDestroyCompositor() = 0;

[joth, 2013/05/16 18:21:42]

the extra layer of delegate delegation is unfortunate extra complexity, but I
don't have any immediate better idea.

+
+   protected:
+    Delegate() {}
+    virtual ~Delegate() {}
+
+   private:
+    DISALLOW_COPY_AND_ASSIGN(Delegate);
+  };
+
+  explicit SynchronousCompositorOutputSurface(Delegate* delegate);
   virtual ~SynchronousCompositorOutputSurface();
 
   // OutputSurface.
   virtual bool ForcedDrawToSoftwareDevice() const OVERRIDE;
   virtual bool BindToClient(cc::OutputSurfaceClient* surface_client) OVERRIDE;
   virtual void Reshape(gfx::Size size) OVERRIDE;
   virtual void SendFrameToParentCompositor(cc::CompositorFrame* frame) OVERRIDE;
   virtual void EnableVSyncNotification(bool enable_vsync) OVERRIDE;
   virtual void SwapBuffers(const cc::LatencyInfo& info) OVERRIDE;
 
-  // SynchronousCompositor.
-  virtual void SetClient(SynchronousCompositorClient* compositor_client)
-      OVERRIDE;
-  virtual bool IsHwReady() OVERRIDE;
-  virtual bool DemandDrawSw(SkCanvas* canvas) OVERRIDE;
-  virtual bool DemandDrawHw(
-      gfx::Size view_size,
-      const gfx::Transform& transform,
-      gfx::Rect clip) OVERRIDE;
+  // Partial SynchronousCompositor API implementation.
+  bool IsHwReady();
+  bool DemandDrawSw(SkCanvas* canvas);
+  bool DemandDrawHw(gfx::Size view_size,
+                    const gfx::Transform& transform,
+                    gfx::Rect clip);
 
  private:
   class SoftwareDevice;
   friend class SoftwareDevice;
 
   void InvokeComposite(const gfx::Transform& transform, gfx::Rect damage_area);
   void UpdateCompositorClientSettings();
   void NotifyCompositorSettingsChanged();
   bool CalledOnValidThread() const;
 
-  SynchronousCompositorClient* compositor_client_;
-  int routing_id_;
+  Delegate* delegate_;
   bool vsync_enabled_;
   bool did_swap_buffer_;
 
   // Only valid (non-NULL) during a DemandDrawSw() call.
   SkCanvas* current_sw_canvas_;
 
   DISALLOW_COPY_AND_ASSIGN(SynchronousCompositorOutputSurface);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_ANDROID_SYNCHRONOUS_COMPOSITOR_OUTPUT_SURFACE_H_