Introduce PaintingContext, which will be used for custom painting

sky/engine/core/painting/PaintingContext.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/PaintingContext.h"
+
+#include "sky/engine/platform/geometry/IntRect.h"
+#include "third_party/skia/include/core/SkCanvas.h"
+
+namespace blink {
+
+PaintingContext::PaintingContext(const FloatRect& bounds)
+{
+    m_displayList = adoptRef(new DisplayList(bounds));
+    m_canvas = m_displayList->beginRecording(enclosingIntRect(bounds).size());
+}
+
+PaintingContext::~PaintingContext()
+{
+}
+
+void PaintingContext::drawCircle(double x, double y, double radius, Paint* paint)
+{
+    if (!m_canvas)
+        return;
+    ASSERT(paint);
+    ASSERT(m_displayList->isRecording());
+    m_canvas->drawCircle(x, y, radius, paint->paint());
+}
+
+void PaintingContext::commit()
+{
+    m_displayList->endRecording();
+    m_canvas = nullptr;
+}
+
+} // namespace blink