Mojo: more idiomatic C++ bindings

mojo/examples/compositor_app/compositor_host.cc

 // 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.
 
 #include "mojo/examples/compositor_app/compositor_host.h"
 
 #include "cc/layers/layer.h"
 #include "cc/layers/solid_color_layer.h"
 #include "cc/output/context_provider.h"
 #include "cc/output/output_surface.h"
@@ skipping 10 matching lines @@
   DCHECK(started);
 
   cc::LayerTreeSettings settings;
   tree_ = cc::LayerTreeHost::CreateThreaded(
       this, NULL, settings, compositor_thread_.message_loop_proxy());
   SetupScene();
 }
 
 CompositorHost::~CompositorHost() {}
 
-void CompositorHost::SetSize(gfx::Size viewport_size) {
+void CompositorHost::SetSize(const gfx::Size& viewport_size) {
   tree_->SetViewportSize(viewport_size);
   tree_->SetLayerTreeHostClientReady();
 }
 
 void CompositorHost::SetupScene() {
   scoped_refptr<cc::Layer> root_layer = cc::SolidColorLayer::Create();
   root_layer->SetBounds(gfx::Size(500, 500));
   root_layer->SetBackgroundColor(SK_ColorBLUE);
   root_layer->SetIsDrawable(true);
   tree_->SetRootLayer(root_layer);
@@ skipping 36 matching lines @@
 void CompositorHost::DidInitializeOutputSurface() {
 }
 
 void CompositorHost::WillCommit() {}
 void CompositorHost::DidCommit() {}
 void CompositorHost::DidCommitAndDrawFrame() {}
 void CompositorHost::DidCompleteSwapBuffers() {}
 
 }  // namespace examples
 }  // namespace mojo