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

cc/trees/layer_tree_host_impl.cc

 // Copyright 2011 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/trees/layer_tree_host_impl.h"
 
 #include <algorithm>
 #include <limits>
 
 #include "base/basictypes.h"
@@ skipping 1881 matching lines @@
   CreateAndSetTileManager(resource_provider_.get(),
                           NULL,
                           GetRendererCapabilities().using_map_image);
   DCHECK(tile_manager_);
 
   SetOffscreenContextProvider(NULL);
 
   client_->SetNeedsCommitOnImplThread();
 }
 
-void LayerTreeHostImpl::SetViewportSize(gfx::Size device_viewport_size) {
+void LayerTreeHostImpl::SetViewportSize(const gfx::Size& device_viewport_size) {
   if (device_viewport_size == device_viewport_size_)
     return;
 
   if (pending_tree_)
     active_tree_->SetViewportSizeInvalid();
 
   device_viewport_size_ = device_viewport_size;
 
   UpdateMaxScrollOffset();
 
   client_->OnCanDrawStateChanged(CanDraw());
   SetFullRootLayerDamage();
 }
 
 void LayerTreeHostImpl::SetOverdrawBottomHeight(float overdraw_bottom_height) {
   if (overdraw_bottom_height == overdraw_bottom_height_)
     return;
   overdraw_bottom_height_ = overdraw_bottom_height;
 
   UpdateMaxScrollOffset();
   SetFullRootLayerDamage();
 }
 
 void LayerTreeHostImpl::SetOverhangUIResource(
     UIResourceId overhang_ui_resource_id,
-    gfx::Size overhang_ui_resource_size) {
+    const gfx::Size& overhang_ui_resource_size) {
   overhang_ui_resource_id_ = overhang_ui_resource_id;
   overhang_ui_resource_size_ = overhang_ui_resource_size;
 }
 
 void LayerTreeHostImpl::SetDeviceScaleFactor(float device_scale_factor) {
   if (device_scale_factor == device_scale_factor_)
     return;
   device_scale_factor_ = device_scale_factor;
 
   UpdateMaxScrollOffset();
@@ skipping 983 matching lines @@
   swap_promise_monitor_.erase(monitor);
 }
 
 void LayerTreeHostImpl::NotifySwapPromiseMonitorsOfSetNeedsRedraw() {
   std::set<SwapPromiseMonitor*>::iterator it = swap_promise_monitor_.begin();
   for (; it != swap_promise_monitor_.end(); it++)
     (*it)->OnSetNeedsRedrawOnImpl();
 }
 
 }  // namespace cc