Prevent synchronous image change notifications during paint

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

 /*
  * Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2004, 2005, 2006 Apple Computer, Inc.  All rights reserved.
  * Copyright (C) 2008-2009 Torch Mobile, Inc.
  *
  * 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 122 matching lines @@
 
     // Animation.
     // We start and stop animating lazily.  Animation starts when the image is
     // rendered, and automatically stops once no observer wants to render the
     // image.
     int repetitionCount(bool imageKnownToBeComplete);  // |imageKnownToBeComplete| should be set if the caller knows the entire image has been decoded.
     bool shouldAnimate();
     void startAnimation(CatchUpAnimation = CatchUp) override;
     void stopAnimation();
     void advanceAnimation(Timer<BitmapImage>*);
+    // Advance the animation and let the next frame get scheduled without
+    // catch-up logic. For large images with slow or heavily-loaded systems,
+    // throwing away data as we go (see destroyDecodedData()) means we can spend
+    // so much time re-decoding data that we are always behind. To prevent this,
+    // we force the next animation to skip the catch up logic.
+    void advanceAnimationWithoutCatchUp(Timer<BitmapImage>*);
 
     // Function that does the real work of advancing the animation.  When
     // skippingFrames is true, we're in the middle of a loop trying to skip over
     // a bunch of animation frames, so we should not do things like decode each
     // one or notify our observers.
     // Returns whether the animation was advanced.
     bool internalAdvanceAnimation(bool skippingFrames);
 
     ImageSource m_source;
     mutable IntSize m_size; // The size to use for the overall image (will just be the size of the first image).
@@ skipping 21 matching lines @@
     mutable bool m_haveSize : 1; // Whether or not our |m_size| member variable has the final overall image size yet.
     bool m_sizeAvailable : 1; // Whether or not we can obtain the size of the first image frame yet from ImageIO.
     mutable bool m_haveFrameCount : 1;
 };
 
 DEFINE_IMAGE_TYPE_CASTS(BitmapImage);
 
 } // namespace blink
 
 #endif