Move image loading out of C++ into Dart

sky/engine/core/loader/CanvasImageLoader.h

-// SKY_ENGINE_CORE_PAINTING_CANVASIMAGE_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_LOADER_CANVASIMAGELOADER_H_
-#define SKY_ENGINE_CORE_LOADER_CANVASIMAGELOADER_H_
-
-#include "mojo/common/data_pipe_drainer.h"
-#include "sky/engine/core/loader/ImageLoaderCallback.h"
-#include "sky/engine/platform/SharedBuffer.h"
-#include "sky/engine/platform/fetcher/MojoFetcher.h"
-#include "sky/engine/tonic/dart_wrappable.h"
-#include "sky/engine/wtf/OwnPtr.h"
-#include "sky/engine/wtf/text/AtomicString.h"
-
-namespace blink {
-
-class CanvasImageLoader : public MojoFetcher::Client,
-                          public mojo::common::DataPipeDrainer::Client,
-                          public RefCounted<CanvasImageLoader>,
-                          public DartWrappable {
-  DEFINE_WRAPPERTYPEINFO();
- public:
-  static PassRefPtr<CanvasImageLoader> create(const String& src, PassOwnPtr<ImageLoaderCallback> callback)
-  {
-    return adoptRef(new CanvasImageLoader(src, callback));
-  }
-  virtual ~CanvasImageLoader();
-
-  // MojoFetcher::Client
-  void OnReceivedResponse(mojo::URLResponsePtr) override;
-
-  // mojo::common::DataPipeDrainer::Client
-  void OnDataAvailable(const void*, size_t) override;
-  void OnDataComplete() override;
-
- private:
-  explicit CanvasImageLoader(const String& src, PassOwnPtr<ImageLoaderCallback> callback);
-
-  OwnPtr<MojoFetcher> fetcher_;
-  OwnPtr<mojo::common::DataPipeDrainer> drainer_;
-  RefPtr<SharedBuffer> buffer_;
-  OwnPtr<ImageLoaderCallback> callback_;
-};
-
-}  // namespace blink
-
-#endif  // SKY_ENGINE_CORE_LOADER_CANVASIMAGELOADER_H_