cc: Don't pass simple well-defined classes by reference.

cc/resources/resource.h

 // 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.
 
 #ifndef CC_RESOURCES_RESOURCE_H_
 #define CC_RESOURCES_RESOURCE_H_
 
 #include "cc/base/cc_export.h"
 #include "cc/resources/resource_provider.h"
 #include "third_party/khronos/GLES2/gl2.h"
 #include "ui/gfx/size.h"
 
 namespace cc {
 
 class CC_EXPORT Resource {
  public:
   Resource() : id_(0) {}
   Resource(unsigned id, gfx::Size size, GLenum format)
       : id_(id),
         size_(size),
         format_(format) {}
 
   ResourceProvider::ResourceId id() const { return id_; }
-  const gfx::Size& size() const { return size_; }
+  gfx::Size size() const { return size_; }
   GLenum format() const { return format_; }
 
   size_t bytes() const;
 
   static size_t BytesPerPixel(GLenum format);
-  static size_t MemorySizeBytes(const gfx::Size& size, GLenum format);
+  static size_t MemorySizeBytes(gfx::Size size, GLenum format);
 
  protected:
   void set_id(ResourceProvider::ResourceId id) { id_ = id; }
-  void set_dimensions(const gfx::Size&, GLenum format);
+  void set_dimensions(gfx::Size size, GLenum format) {
+    size_ = size;
+    format_ = format;
+  }
 
  private:
   ResourceProvider::ResourceId id_;
   gfx::Size size_;
   GLenum format_;
 
   DISALLOW_COPY_AND_ASSIGN(Resource);
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_RESOURCE_H_