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

cc/layers/io_surface_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/io_surface_layer_impl.h"
 
 #include "base/strings/stringprintf.h"
 #include "cc/layers/quad_sink.h"
 #include "cc/output/gl_renderer.h"  // For the GLC() macro.
 #include "cc/output/output_surface.h"
@@ skipping 113 matching lines @@
 }
 
 void IOSurfaceLayerImpl::ReleaseResources() {
   // We don't have a valid texture ID in the new context; however,
   // the IOSurface is still valid.
   DestroyTexture();
   io_surface_changed_ = true;
 }
 
 void IOSurfaceLayerImpl::SetIOSurfaceProperties(unsigned io_surface_id,
-                                                gfx::Size size) {
+                                                const gfx::Size& size) {
   if (io_surface_id_ != io_surface_id)
     io_surface_changed_ = true;
 
   io_surface_id_ = io_surface_id;
   io_surface_size_ = size;
 }
 
 const char* IOSurfaceLayerImpl::LayerTypeAsString() const {
   return "cc::IOSurfaceLayerImpl";
 }
 
 }  // namespace cc