Add APIs for dynamic display lists, using SkDrawable and SkPictureRecorder::endRecordingAsDrawable.

sky/engine/core/painting/PictureRecorder.h

 // Copyright 2015 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 SKY_ENGINE_CORE_PAINTING_PICTURERECORDER_H_
 #define SKY_ENGINE_CORE_PAINTING_PICTURERECORDER_H_
 
 #include "sky/engine/tonic/dart_wrappable.h"
 #include "sky/engine/wtf/PassRefPtr.h"
 #include "sky/engine/wtf/RefCounted.h"
 #include "third_party/skia/include/core/SkPictureRecorder.h"
 
 namespace blink {
 
+class Canvas;
+class Drawable;
 class Picture;
-class Canvas;
 
 class PictureRecorder : public RefCounted<PictureRecorder>,
                         public DartWrappable {
     DEFINE_WRAPPERTYPEINFO();
 public:
     static PassRefPtr<PictureRecorder> create()
     {
         return adoptRef(new PictureRecorder());
     }
 
     ~PictureRecorder();
 
     // PassRefPtr<Canvas> beginRecording(double width, double height);
     SkCanvas* beginRecording(double width, double height);
     PassRefPtr<Picture> endRecording();
+    PassRefPtr<Drawable> endRecordingAsDrawable();
     bool isRecording();
 
     void set_canvas(PassRefPtr<Canvas> canvas);
 
 private:
         PictureRecorder();
 
         OwnPtr<SkPictureRecorder> m_pictureRecorder;
         RefPtr<Canvas> m_canvas;
 };
 
 } // namespace blink
 
 #endif  // SKY_ENGINE_CORE_PAINTING_PICTURERECORDER_H_