Cancel GPU acceleration for 2D canvas when drawing very large images

third_party/WebKit/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 263 matching lines @@
 bool HTMLCanvasElement::shouldBeDirectComposited() const
 {
     return (m_context && m_context->isAccelerated()) || (hasImageBuffer() && buffer()->isExpensiveToPaint()) || (!!m_surfaceLayerBridge);
 }
 
 bool HTMLCanvasElement::isPaintable() const
 {
     return (m_context && m_context->isPaintable()) || ImageBuffer::canCreateImageBuffer(size());
 }
 
+bool HTMLCanvasElement::isAccelerated() const
+{
+    return m_context && m_context->isAccelerated();
+}
+
 void HTMLCanvasElement::didDraw(const FloatRect& rect)
 {
     if (rect.isEmpty())
         return;
     m_imageBufferIsClear = false;
     clearCopiedImage();
     if (layoutObject())
         layoutObject()->setMayNeedPaintInvalidation();
     if (m_context && m_context->is2d() && m_context->shouldAntialias() && page() && page()->deviceScaleFactor() > 1.0f) {
         FloatRect inflatedRect = rect;
@@ skipping 1004 matching lines @@
 bool HTMLCanvasElement::createSurfaceLayer()
 {
     DCHECK(!m_surfaceLayerBridge);
     mojom::blink::OffscreenCanvasSurfacePtr service;
     Platform::current()->interfaceProvider()->getInterface(mojo::GetProxy(&service));
     m_surfaceLayerBridge = wrapUnique(new CanvasSurfaceLayerBridge(std::move(service)));
     return m_surfaceLayerBridge->createSurfaceLayer(this->width(), this->height());
 }
 
 } // namespace blink