ui: Eliminate allocating gfx::Canvas on the heap for every view.

ui/compositor/layer.cc

 // Copyright (c) 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 "ui/compositor/layer.h"
 
 #include <algorithm>
 
 #include "base/auto_reset.h"
 #include "base/command_line.h"
@@ skipping 729 matching lines @@
 void Layer::RequestCopyOfOutput(scoped_ptr<cc::CopyOutputRequest> request) {
   cc_layer_->RequestCopyOfOutput(request.Pass());
 }
 
 void Layer::PaintContents(
     SkCanvas* sk_canvas,
     const gfx::Rect& clip,
     ContentLayerClient::PaintingControlSetting painting_control) {
   TRACE_EVENT1("ui", "Layer::PaintContents", "name", name_);
   ClearDamagedRects();
-  scoped_ptr<gfx::Canvas> canvas(gfx::Canvas::CreateCanvasWithoutScaling(
-      sk_canvas, device_scale_factor_));
-  if (delegate_)
-    delegate_->OnPaintLayer(PaintContext(canvas.get(), clip));
+  if (delegate_) {
+    gfx::Canvas canvas(sk_canvas, device_scale_factor_);
+    delegate_->OnPaintLayer(PaintContext(&canvas, clip));
+  }
 }
 
 void Layer::PaintContentsToDisplayList(
     cc::DisplayItemList* display_list,
     const gfx::Rect& clip,
     ContentLayerClient::PaintingControlSetting painting_control) {
   TRACE_EVENT1("ui", "Layer::PaintContentsToDisplayList", "name", name_);
   gfx::Rect local_bounds(bounds().size());
   gfx::Rect invalidation(
       gfx::IntersectRects(damaged_region_.bounds(), local_bounds));
@@ skipping 329 matching lines @@
       children_.end(),
       std::bind2nd(std::mem_fun(&Layer::RemoveAnimatorsInTreeFromCollection),
                    collection));
 }
 
 bool Layer::IsAnimating() const {
   return animator_.get() && animator_->is_animating();
 }
 
 }  // namespace ui