Mojo: more idiomatic C++ bindings

mojo/examples/compositor_app/compositor_host.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 MOJO_EXAMPLES_COMPOSITOR_APP_COMPOSITOR_HOST_H_
 #define MOJO_EXAMPLES_COMPOSITOR_APP_COMPOSITOR_HOST_H_
 
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/threading/thread.h"
 #include "cc/trees/layer_tree_host_client.h"
 #include "mojo/public/cpp/system/core.h"
 #include "ui/gfx/size.h"
 
 namespace cc {
 class Layer;
 class LayerTreeHost;
 }  // namespace cc
 
 namespace mojo {
 namespace examples {
 class GLES2ClientImpl;
 
 class CompositorHost : public cc::LayerTreeHostClient {
  public:
   explicit CompositorHost(ScopedMessagePipeHandle gl_pipe);
   virtual ~CompositorHost();
 
-  void SetSize(gfx::Size viewport_size);
+  void SetSize(const gfx::Size& viewport_size);
 
   // cc::LayerTreeHostClient implementation.
   virtual void WillBeginMainFrame(int frame_id) OVERRIDE;
   virtual void DidBeginMainFrame() OVERRIDE;
   virtual void Animate(base::TimeTicks frame_begin_time) OVERRIDE;
   virtual void Layout() OVERRIDE;
   virtual void ApplyScrollAndScale(const gfx::Vector2d& scroll_delta,
                                    float page_scale) OVERRIDE;
   virtual scoped_ptr<cc::OutputSurface> CreateOutputSurface(bool fallback)
       OVERRIDE;
   virtual void DidInitializeOutputSurface() OVERRIDE;
   virtual void WillCommit() OVERRIDE;
   virtual void DidCommit() OVERRIDE;
   virtual void DidCommitAndDrawFrame() OVERRIDE;
   virtual void DidCompleteSwapBuffers() OVERRIDE;
 
  private:
   void SetupScene();
 
   ScopedMessagePipeHandle gl_pipe_;
   scoped_ptr<cc::LayerTreeHost> tree_;
   scoped_refptr<cc::Layer> child_layer_;
   base::Thread compositor_thread_;
 };
 
 }  // namespace examples
 }  // namespace mojo
 
 #endif  // MOJO_EXAMPLES_COMPOSITOR_APP_COMPOSITOR_HOST_H_