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

sky/engine/core/painting/LayerDrawLooperBuilder.h

Index: sky/engine/core/painting/LayerDrawLooperBuilder.h
diff --git a/sky/engine/core/painting/LayerDrawLooperBuilder.h b/sky/engine/core/painting/LayerDrawLooperBuilder.h
new file mode 100644
index 0000000000000000000000000000000000000000..e83dadabd03bbf7ed6803fdcb25107b9a2e24fae
--- /dev/null
+++ b/sky/engine/core/painting/LayerDrawLooperBuilder.h
@@ -0,0 +1,40 @@
+// 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_LAYERDRAWLOOPERBUILDER_H_
+#define SKY_ENGINE_CORE_PAINTING_LAYERDRAWLOOPERBUILDER_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/effects/SkLayerDrawLooper.h"
+
+namespace blink {
+
+class DrawLooper;
+class DrawLooperAddLayerCallback;
+class DrawLooperLayerInfo;
+
+class LayerDrawLooperBuilder : public RefCounted<LayerDrawLooperBuilder>, public DartWrappable {
+    DEFINE_WRAPPERTYPEINFO();
+public:
+    ~LayerDrawLooperBuilder() override;
+    static PassRefPtr<LayerDrawLooperBuilder> create()
+    {
+        return adoptRef(new LayerDrawLooperBuilder);
+    }
+
+    PassRefPtr<DrawLooper> build();
+    void addLayerOnTop(DrawLooperLayerInfo* layerInfo,
+                       PassOwnPtr<DrawLooperAddLayerCallback>);
+
+private:
+    LayerDrawLooperBuilder();
+
+    SkLayerDrawLooper::Builder m_drawLooperBuilder;
+};
+
+} // namespace blink
+
+#endif  // SKY_ENGINE_CORE_PAINTING_LAYERDRAWLOOPERBUILDER_H_