Add support for Animated PNG

third_party/WebKit/Source/platform/image-decoders/ImageDecoder.h

Index: third_party/WebKit/Source/platform/image-decoders/ImageDecoder.h
diff --git a/third_party/WebKit/Source/platform/image-decoders/ImageDecoder.h b/third_party/WebKit/Source/platform/image-decoders/ImageDecoder.h
index 85e16496781e8d65850d246c637f4cf21e41c203..4ccea9b8c3a98ef9f99071cd0c70cdefe7fb6dca 100644
--- a/third_party/WebKit/Source/platform/image-decoders/ImageDecoder.h
+++ b/third_party/WebKit/Source/platform/image-decoders/ImageDecoder.h
@@ -406,7 +406,7 @@ class PLATFORM_EXPORT ImageDecoder {
 
   // This methods gets called at the end of initFrameBuffer. Subclasses can do
   // format specific initialization, for e.g. alpha settings, here.
-  virtual void onInitFrameBuffer(size_t){};
+  virtual bool onInitFrameBuffer(size_t) { return true; };
 
   // Called by initFrameBuffer to determine if it can take the bitmap of the
   // previous frame. This condition is different for GIF and WEBP.