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

cc/layers/picture_layer_impl.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/picture_layer_impl.h"
 
 #include <algorithm>
 #include <limits>
 
 #include "base/time/time.h"
@@ skipping 496 matching lines @@
       should_use_gpu_rasterization())
     return NULL;
   for (size_t i = 0; i < twin_layer_->tilings_->num_tilings(); ++i)
     if (twin_layer_->tilings_->tiling_at(i)->contents_scale() ==
         tiling->contents_scale())
       return twin_layer_->tilings_->tiling_at(i);
   return NULL;
 }
 
 gfx::Size PictureLayerImpl::CalculateTileSize(
-    gfx::Size content_bounds) const {
+    const gfx::Size& content_bounds) const {
   if (is_mask_) {
     int max_size = layer_tree_impl()->MaxTextureSize();
     return gfx::Size(
         std::min(max_size, content_bounds.width()),
         std::min(max_size, content_bounds.height()));
   }
 
   int max_texture_size =
       layer_tree_impl()->resource_provider()->max_texture_size();
 
@@ skipping 703 matching lines @@
 size_t PictureLayerImpl::GPUMemoryUsageInBytes() const {
   const_cast<PictureLayerImpl*>(this)->DoPostCommitInitializationIfNeeded();
   return tilings_->GPUMemoryUsageInBytes();
 }
 
 void PictureLayerImpl::RunMicroBenchmark(MicroBenchmarkImpl* benchmark) {
   benchmark->RunOnLayer(this);
 }
 
 }  // namespace cc