[#7] Pass gfx structs by const ref (gfx::Size)

cc/layers/heads_up_display_layer.cc

 // Copyright 2012 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 "cc/layers/heads_up_display_layer.h"
 
 #include <algorithm>
 
 #include "base/debug/trace_event.h"
 #include "cc/layers/heads_up_display_layer_impl.h"
 #include "cc/trees/layer_tree_host.h"
 
 namespace cc {
 
 scoped_refptr<HeadsUpDisplayLayer> HeadsUpDisplayLayer::Create() {
   return make_scoped_refptr(new HeadsUpDisplayLayer());
 }
 
 HeadsUpDisplayLayer::HeadsUpDisplayLayer() {}
 
 HeadsUpDisplayLayer::~HeadsUpDisplayLayer() {}
 
 void HeadsUpDisplayLayer::PrepareForCalculateDrawProperties(
-    gfx::Size device_viewport, float device_scale_factor) {
+    const gfx::Size& device_viewport, float device_scale_factor) {
   gfx::Size device_viewport_in_layout_pixels = gfx::Size(
       device_viewport.width() / device_scale_factor,
       device_viewport.height() / device_scale_factor);
 
   gfx::Size bounds;
   gfx::Transform matrix;
   matrix.MakeIdentity();
 
   if (layer_tree_host()->debug_state().ShowHudRects()) {
     int max_texture_size =
@@ skipping 14 matching lines @@
 
 bool HeadsUpDisplayLayer::DrawsContent() const { return true; }
 
 scoped_ptr<LayerImpl> HeadsUpDisplayLayer::CreateLayerImpl(
     LayerTreeImpl* tree_impl) {
   return HeadsUpDisplayLayerImpl::Create(tree_impl, layer_id_).
       PassAs<LayerImpl>();
 }
 
 }  // namespace cc