Do compositing update when switching from software to accelerated canvas

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 1217 matching lines @@
   if (ExpensiveCanvasHeuristicParameters::EnableAccelerationToAvoidReadbacks &&
       source->isAccelerated() && !buffer()->isAccelerated() &&
       shouldAccelerate(IgnoreResourceLimitCriteria)) {
     OpacityMode opacityMode =
         m_context->creationAttributes().alpha() ? NonOpaque : Opaque;
     int msaaSampleCount = 0;
     std::unique_ptr<ImageBufferSurface> surface =
         createAcceleratedImageBufferSurface(opacityMode, &msaaSampleCount);
     if (surface) {
       buffer()->setSurface(std::move(surface));
+      setNeedsCompositingUpdate();
     }
   }
 }
 
 PassRefPtr<Image> HTMLCanvasElement::getSourceImageForCanvas(
     SourceImageStatus* status,
     AccelerationHint hint,
     SnapshotReason reason,
     const FloatSize&) const {
   if (!width() || !height()) {
@@ skipping 214 matching lines @@
     // Creates a placeholder layer first before Surface is created.
     m_surfaceLayerBridge->createSolidColorLayer();
   }
 }
 
 void HTMLCanvasElement::OnWebLayerReplaced() {
   setNeedsCompositingUpdate();
 }
 
 }  // namespace blink