cc: Make LayerTreeHostImpl::SwapBuffers not virtual.

cc/test/fake_output_surface.h

Index: cc/test/fake_output_surface.h
diff --git a/cc/test/fake_output_surface.h b/cc/test/fake_output_surface.h
index 8fcc04a4cfd2549b42465a7c8bbdb276d62b476c..ca6676de64fec26141355e4fcf15aa8e3a2e9c74 100644
--- a/cc/test/fake_output_surface.h
+++ b/cc/test/fake_output_surface.h
@@ -109,6 +109,7 @@ class FakeOutputSurface : public OutputSurface {
 
   OutputSurfaceClient* client() { return client_; }
   bool BindToClient(OutputSurfaceClient* client) override;
+  void DetachFromClient() override;
 
   void set_framebuffer(GLint framebuffer, GLenum format) {
     framebuffer_ = framebuffer;
@@ -123,8 +124,6 @@ class FakeOutputSurface : public OutputSurface {
     return resources_held_by_parent_;
   }
 
-  void ReturnResource(unsigned id, CompositorFrameAck* ack);
-
   bool HasExternalStencilTest() const override;
 
   bool SurfaceIsSuspendForRecycle() const override;
@@ -149,6 +148,8 @@ class FakeOutputSurface : public OutputSurface {
     return last_swap_rect_;
   }
 
+  void ReturnResourcesHeldByParent();
+
  protected:
   FakeOutputSurface(scoped_refptr<ContextProvider> context_provider,
                     scoped_refptr<ContextProvider> worker_context_provider,