Initial implementation of display list backed 2D canvases

Source/platform/graphics/skia/OpaqueRegionSkia.cpp

 /*
  * Copyright (c) 2012, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 26 matching lines @@
 #include "SkColorFilter.h"
 #include "SkShader.h"
 
 namespace blink {
 
 OpaqueRegionSkia::OpaqueRegionSkia()
     : m_opaqueRect(SkRect::MakeEmpty())
 {
 }
 
+void OpaqueRegionSkia::reset()
+{
+    ASSERT(m_canvasLayerStack.isEmpty());
+    m_opaqueRect = SkRect::MakeEmpty();
+}
+
 IntRect OpaqueRegionSkia::asRect() const
 {
     // Returns the largest enclosed rect.
     // TODO: actually, this logic looks like its returning the smallest.
     //       to return largest, shouldn't we take floor of left/top
     //       and the ceil of right/bottom?
     int left = SkScalarCeilToInt(m_opaqueRect.fLeft);
     int top = SkScalarCeilToInt(m_opaqueRect.fTop);
     int right = SkScalarFloorToInt(m_opaqueRect.fRight);
     int bottom = SkScalarFloorToInt(m_opaqueRect.fBottom);
@@ skipping 376 matching lines @@
     opaqueRect.setEmpty();
 }
 
 SkRect& OpaqueRegionSkia::currentTrackingOpaqueRect()
 {
     // If we are drawing into a canvas layer, then track the opaque rect in that layer.
     return m_canvasLayerStack.isEmpty() ? m_opaqueRect : m_canvasLayerStack.last().opaqueRect;
 }
 
 } // namespace blink