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

cc/resources/bitmap_skpicture_content_layer_updater.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/resources/bitmap_skpicture_content_layer_updater.h"
 
 #include "base/time/time.h"
 #include "cc/debug/rendering_stats_instrumentation.h"
 #include "cc/resources/layer_painter.h"
 #include "cc/resources/prioritized_resource.h"
 #include "cc/resources/resource_update_queue.h"
 #include "third_party/skia/include/core/SkBitmapDevice.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 
 namespace cc {
 
 BitmapSkPictureContentLayerUpdater::Resource::Resource(
     BitmapSkPictureContentLayerUpdater* updater,
     scoped_ptr<PrioritizedResource> texture)
     : ContentLayerUpdater::Resource(texture.Pass()), updater_(updater) {}
 
 void BitmapSkPictureContentLayerUpdater::Resource::Update(
     ResourceUpdateQueue* queue,
     const gfx::Rect& source_rect,
-    gfx::Vector2d dest_offset,
+    const gfx::Vector2d& dest_offset,
     bool partial_update) {
   bitmap_.setConfig(
       SkBitmap::kARGB_8888_Config, source_rect.width(), source_rect.height(), 0,
       updater_->layer_is_opaque() ? kOpaque_SkAlphaType : kPremul_SkAlphaType);
   bitmap_.allocPixels();
   SkBitmapDevice device(bitmap_);
   SkCanvas canvas(&device);
   updater_->PaintContentsRect(&canvas, source_rect);
 
   ResourceUpdate upload = ResourceUpdate::Create(
@@ skipping 42 matching lines @@
       rendering_stats_instrumentation_->StartRecording();
   DrawPicture(canvas);
   base::TimeDelta duration =
       rendering_stats_instrumentation_->EndRecording(start_time);
   rendering_stats_instrumentation_->AddRaster(
       duration,
       source_rect.width() * source_rect.height());
 }
 
 }  // namespace cc