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

sky/engine/core/painting/Paint.cpp

 // 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/Paint.h"
 
+#include "sky/engine/core/painting/DrawLooper.h"
+
 namespace blink {
 
 Paint::Paint()
+    : m_paint(&m_inline_paint)
 {
 }
 
+Paint::Paint(SkPaint* paint)
+    : m_paint(paint)
+{
+}
+
 Paint::~Paint()
 {
 }
 
+void Paint::setDrawLooper(DrawLooper* looper)
+{
+    ASSERT(looper);
+    m_paint->setLooper(looper->looper());
+}
+
 } // namespace blink