cc: Use a ListContainer for DisplayItemList to reduce allocations.

cc/resources/drawing_display_item.cc

 // 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.
 
 #include "cc/resources/drawing_display_item.h"
 
 #include <string>
 
 #include "base/strings/stringprintf.h"
 #include "base/trace_event/trace_event_argument.h"
 #include "cc/debug/picture_debug_util.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "third_party/skia/include/core/SkDrawPictureCallback.h"
 #include "third_party/skia/include/core/SkMatrix.h"
 #include "third_party/skia/include/core/SkPicture.h"
 #include "third_party/skia/include/utils/SkPictureUtils.h"
 
 namespace cc {
 
-DrawingDisplayItem::DrawingDisplayItem(skia::RefPtr<SkPicture> picture)
-    : picture_(picture) {
+DrawingDisplayItem::DrawingDisplayItem() {
 }
 
 DrawingDisplayItem::~DrawingDisplayItem() {
 }
 
+void DrawingDisplayItem::SetNew(skia::RefPtr<SkPicture> picture) {
+  picture_ = picture.Pass();
+}
+
 void DrawingDisplayItem::Raster(SkCanvas* canvas,
                                 SkDrawPictureCallback* callback) const {
   // SkPicture always does a wrapping save/restore on the canvas, so it is not
   // necessary here.
   if (callback)
     picture_->playback(canvas, callback);
   else
     canvas->drawPicture(picture_.get());
 }
 
@@ skipping 18 matching lines @@
       "cullRect",
       base::StringPrintf("[%f,%f,%f,%f]", picture_->cullRect().x(),
                          picture_->cullRect().y(), picture_->cullRect().width(),
                          picture_->cullRect().height()));
   std::string b64_picture;
   PictureDebugUtil::SerializeAsBase64(picture_.get(), &b64_picture);
   array->SetString("skp64", b64_picture);
   array->EndDictionary();
 }
 
-scoped_ptr<DrawingDisplayItem> DrawingDisplayItem::Clone() {
-  return Create(picture_);
+void DrawingDisplayItem::CloneTo(DrawingDisplayItem* item) const {
+  item->SetNew(picture_);
 }
 
 }  // namespace cc