Delay SVGImage animations reset while being updated.

third_party/WebKit/Source/core/svg/graphics/SVGImageChromeClient.cpp

 /*
  * Copyright (C) 2012 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 83 matching lines @@
     //
     // TODO(Oilpan): move (SVG)Image to the Oilpan heap, and avoid
     // this explicit lifetime check.
     if (ThreadHeap::willObjectBeLazilySwept(m_image->getImageObserver()))
         return;
 
     // serviceScriptedAnimations runs requestAnimationFrame callbacks, but SVG
     // images can't have any so we assert there's no script.
     ScriptForbiddenScope forbidScript;
 
-    // The calls below may trigger GCs, so set up the required persistent
-    // reference on the ImageResource which owns this SVGImage. By transitivity,
-    // that will keep this SVGImageChromeClient object alive.
-    Persistent<ImageObserver> protect(m_image->getImageObserver());
-    m_image->frameView()->page()->animator().serviceScriptedAnimations(monotonicallyIncreasingTime());
+    // The call below may trigger GCs, so set up the required reference
+    // to the ImageObserver (an ImageResource) which owns this SVGImage.
+    // By transitivity, that will keep this SVGImageChromeClient object alive.
+    //
+    // The update scope will additionally prevent the GCs from indirectly
+    // triggering animations reset over m_image should the ImageResource become
+    // otherwise unreferenced.
+    {
+        SVGImage::UpdateAnimationScope scope(m_image);
+        m_image->frameView()->page()->animator().serviceScriptedAnimations(monotonicallyIncreasingTime());
+    }
     m_image->frameView()->updateAllLifecyclePhases();
 }
 
 } // namespace blink