[#6]Pass gfx structs by const ref (gfx::Vector2d)

cc/resources/prioritized_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_PRIORITIZED_RESOURCE_H_
 #define CC_RESOURCES_PRIORITIZED_RESOURCE_H_
 
 #include "base/basictypes.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 63 matching lines @@
   // on a call-order basis. We might want to just remove this in the future
   // (carefully) and just make sure we don't regress OOMs situations.
   bool RequestLate();
 
   // Update pixels of backing resource from image. This functions will aquire
   // the backing if needed.
   void SetPixels(ResourceProvider* resource_provider,
                  const uint8_t* image,
                  const gfx::Rect& image_rect,
                  const gfx::Rect& source_rect,
-                 gfx::Vector2d dest_offset);
+                 const gfx::Vector2d& dest_offset);
 
   ResourceProvider::ResourceId resource_id() const {
     return backing_ ? backing_->id() : 0;
   }
 
   // Self-managed textures are accounted for when prioritizing other textures,
   // but they are not allocated/recycled/deleted, so this needs to be done
   // externally. CanAcquireBackingTexture() indicates if the texture would have
   // been allowed given its priority.
   void set_is_self_managed(bool is_self_managed) {
@@ skipping 81 matching lines @@
 
   Backing* backing_;
   PrioritizedResourceManager* manager_;
 
   DISALLOW_COPY_AND_ASSIGN(PrioritizedResource);
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_PRIORITIZED_RESOURCE_H_