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

sky/engine/core/painting/DrawLooperLayerInfo.h

Index: sky/engine/core/painting/DrawLooperLayerInfo.h
diff --git a/sky/engine/core/painting/DrawLooperLayerInfo.h b/sky/engine/core/painting/DrawLooperLayerInfo.h
new file mode 100644
index 0000000000000000000000000000000000000000..4a6731005baa64420229ffcff0710f019647594f
--- /dev/null
+++ b/sky/engine/core/painting/DrawLooperLayerInfo.h
@@ -0,0 +1,41 @@
+// 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) { m_layerInfo.fPaintBits = bits; }
+    void setColorMode(unsigned mode) {
+        m_layerInfo.fColorMode = static_cast<SkXfermode::Mode>(mode);
+    }
+    void setOffset(float x, float y) { m_layerInfo.fOffset.set(x, y); }
+    void setPostTranslate(bool val) { m_layerInfo.fPostTranslate = val; }
+
+    SkLayerDrawLooper::LayerInfo layerInfo() { return m_layerInfo; }
+
+private:
+    DrawLooperLayerInfo();
+
+    SkLayerDrawLooper::LayerInfo m_layerInfo;
+};
+
+} // namespace blink
+
+#endif  // SKY_ENGINE_CORE_PAINTING_DRAWLOOPERLAYERINFO_H_