Make CanvasRenderingContext2D use SkCanvas directly

Source/core/html/HTMLCanvasElement.cpp

 /*
  * Copyright (C) 2004, 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 682 matching lines @@
     if (checkedExternallyAllocatedMemory.safeGet(externallyAllocatedMemory) == CheckedState::DidOverflow)
         externallyAllocatedMemory = std::numeric_limits<intptr_t>::max();
 
     // Subtracting two intptr_t that are known to be positive will never underflow.
     v8::Isolate::GetCurrent()->AdjustAmountOfExternalAllocatedMemory(externallyAllocatedMemory - m_externallyAllocatedMemory);
     m_externallyAllocatedMemory = externallyAllocatedMemory;
 }
 
 GraphicsContext* HTMLCanvasElement::drawingContext() const
 {
-    return buffer() ? m_imageBuffer->context() : 0;
+    return buffer() ? m_imageBuffer->context() : nullptr;
 }
 
 GraphicsContext* HTMLCanvasElement::existingDrawingContext() const
 {
     if (!hasImageBuffer())
         return nullptr;
 
     return drawingContext();
 }
 
+SkCanvas* HTMLCanvasElement::drawingCanvas() const
+{
+    return buffer() ? m_imageBuffer->canvas() : nullptr;
+}
+
+SkCanvas* HTMLCanvasElement::existingDrawingCanvas() const
+{
+    if (!hasImageBuffer())
+        return nullptr;
+
+    return m_imageBuffer->canvas();
+}
+
 ImageBuffer* HTMLCanvasElement::buffer() const
 {
     ASSERT(m_context);
     if (!hasImageBuffer() && !m_didFailToCreateImageBuffer)
         const_cast<HTMLCanvasElement*>(this)->createImageBuffer();
     return m_imageBuffer.get();
 }
 
 void HTMLCanvasElement::ensureUnacceleratedImageBuffer()
 {
@@ skipping 112 matching lines @@
 {
     return !originClean();
 }
 
 FloatSize HTMLCanvasElement::sourceSize() const
 {
     return FloatSize(width(), height());
 }
 
 }