cc: Use a ListContainer for DisplayItemList to reduce allocations.

cc/resources/drawing_display_item.h

 // Copyright 2014 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_DRAWING_DISPLAY_ITEM_H_
 #define CC_RESOURCES_DRAWING_DISPLAY_ITEM_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "cc/base/cc_export.h"
 #include "cc/resources/display_item.h"
 #include "skia/ext/refptr.h"
 #include "ui/gfx/geometry/point_f.h"
 
 class SkCanvas;
 class SkDrawPictureCallback;
 class SkPicture;
 
 namespace cc {
 
 class CC_EXPORT DrawingDisplayItem : public DisplayItem {
  public:
+  DrawingDisplayItem();
   ~DrawingDisplayItem() override;
 
-  static scoped_ptr<DrawingDisplayItem> Create(
-      skia::RefPtr<SkPicture> picture) {
-    return make_scoped_ptr(new DrawingDisplayItem(picture));
-  }
+  void SetNew(skia::RefPtr<SkPicture> picture);
 
   void Raster(SkCanvas* canvas, SkDrawPictureCallback* callback) const override;
 
   bool IsSuitableForGpuRasterization() const override;
   int ApproximateOpCount() const override;
   size_t PictureMemoryUsage() const override;
   void AsValueInto(base::trace_event::TracedValue* array) const override;
 
-  scoped_ptr<DrawingDisplayItem> Clone();
+  void CloneTo(DrawingDisplayItem* item) const;
 
  protected:
   explicit DrawingDisplayItem(skia::RefPtr<SkPicture> picture);
 
  private:
   skia::RefPtr<SkPicture> picture_;
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_DRAWING_DISPLAY_ITEM_H_