Sky: Add a DrawLooper interface to the painting API to be used for shadows.

sky/engine/core/painting/DrawLooperLayerInfo.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_DRAWLOOPERLAYERINFO_H_
+#define SKY_ENGINE_CORE_PAINTING_DRAWLOOPERLAYERINFO_H_
+
+#include "dart/runtime/include/dart_api.h"
+#include "sky/engine/tonic/dart_wrappable.h"
+#include "third_party/skia/include/effects/SkLayerDrawLooper.h"
+
+namespace blink {
+
+class DrawLooperLayerInfo : public RefCounted<DrawLooperLayerInfo>,
+                            public DartWrappable {
+  DEFINE_WRAPPERTYPEINFO();
+ public:
+  static PassRefPtr<DrawLooperLayerInfo> create()
+  {
+    return adoptRef(new DrawLooperLayerInfo);
+  }
+  ~DrawLooperLayerInfo() override;
+
+  void setPaintBits(unsigned bits) { layer_info_.fPaintBits = bits; }
+  void setColorMode(unsigned mode) {
+    layer_info_.fColorMode = static_cast<SkXfermode::Mode>(mode);
+  }
+  void setOffset(float x, float y) { layer_info_.fOffset.set(x, y); }
+  void setPostTranslate(bool val) { layer_info_.fPostTranslate = val; }
+
+  const SkLayerDrawLooper::LayerInfo& layer_info() const { return layer_info_; }
+
+ private:
+  DrawLooperLayerInfo();
+
+  SkLayerDrawLooper::LayerInfo layer_info_;
+};
+
+} // namespace blink
+
+#endif  // SKY_ENGINE_CORE_PAINTING_DRAWLOOPERLAYERINFO_H_