Avoid GPU readback in tex(Sub)Image2D(ImageBitmap)

third_party/WebKit/Source/platform/graphics/BitmapImage.cpp

 /*
  * Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2004, 2005, 2006, 2008 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 324 matching lines @@
 }
 
 float BitmapImage::frameDurationAtIndex(size_t index)
 {
     if (index < m_frames.size() && m_frames[index].m_haveMetadata)
         return m_frames[index].m_duration;
 
     return m_source.frameDurationAtIndex(index);
 }
 
-PassRefPtr<SkImage> BitmapImage::imageForCurrentFrame()
+PassRefPtr<SkImage> BitmapImage::imageForCurrentFrame(WebGraphicsContext3DProvider* contextProvider)
 {
     return frameAtIndex(currentFrame());

[Justin Novosad, 2016/06/07 15:11:07]

If this method is not going to look at contextProvider, it should at least check
that the SkImage is never texture backed.

[xidachen, 2016/06/07 17:49:53]

In my opinion, if this method is called in a test that is running under
virtual/gpu, then the SkImage can be texture-backed.

 }
 
 PassRefPtr<Image> BitmapImage::imageForDefaultFrame()
 {
     if (frameCount() > 1) {
         RefPtr<SkImage> firstFrame = frameAtIndex(0);
         if (firstFrame)
             return StaticBitmapImage::create(firstFrame);
     }
 
@@ skipping 231 matching lines @@
 
     // We need to draw this frame if we advanced to it while not skipping, or if
     // while trying to skip frames we hit the last frame and thus had to stop.
     if (skippingFrames != advancedAnimation)
         getImageObserver()->animationAdvanced(this);
 
     return advancedAnimation;
 }
 
 } // namespace blink