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

sky/engine/core/painting/LayerDrawLooperBuilder.cpp

Index: sky/engine/core/painting/LayerDrawLooperBuilder.cpp
diff --git a/sky/engine/core/painting/LayerDrawLooperBuilder.cpp b/sky/engine/core/painting/LayerDrawLooperBuilder.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..17b4b6e04449ef96cb61370e3bf68cb2210b5d0c
--- /dev/null
+++ b/sky/engine/core/painting/LayerDrawLooperBuilder.cpp
@@ -0,0 +1,37 @@
+// 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.
+
+#include "sky/engine/config.h"
+#include "sky/engine/core/painting/LayerDrawLooperBuilder.h"
+
+#include "sky/engine/core/painting/DrawLooper.h"
+#include "sky/engine/core/painting/DrawLooperAddLayerCallback.h"
+#include "sky/engine/core/painting/DrawLooperLayerInfo.h"
+#include "sky/engine/core/painting/Paint.h"
+
+namespace blink {
+
+LayerDrawLooperBuilder::LayerDrawLooperBuilder()
+{
+}
+
+LayerDrawLooperBuilder::~LayerDrawLooperBuilder()
+{
+}
+
+PassRefPtr<DrawLooper> LayerDrawLooperBuilder::build()
+{
+    return DrawLooper::create(adoptRef(m_drawLooperBuilder.detachLooper()));
+}
+
+void LayerDrawLooperBuilder::addLayerOnTop(
+    DrawLooperLayerInfo* layerInfo,
+    PassOwnPtr<DrawLooperAddLayerCallback> callback)
+{
+    SkPaint* skPaint = m_drawLooperBuilder.addLayerOnTop(layerInfo->layerInfo());
+    RefPtr<Paint> paint = Paint::createWithWeakRef(skPaint);
+    callback->handleEvent(paint.get());
+}
+
+} // namespace blink