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 de85ae0cfac38c1ec639927926eaff9bc04a4254..fa0a989994df1bcca5748e9c2570c18a630631c2 100644
--- a/third_party/WebKit/Source/platform/image-decoders/ImageDecoder.h
+++ b/third_party/WebKit/Source/platform/image-decoders/ImageDecoder.h
@@ -258,13 +258,15 @@ class PLATFORM_EXPORT ImageDecoder {
   // and returns true. Otherwise returns false.
   virtual bool hotSpot(IntPoint&) const { return false; }
 
-  virtual void setMemoryAllocator(SkBitmap::Allocator* allocator) {
+  void setMemoryAllocator(SkBitmap::Allocator* allocator) {
     // FIXME: this doesn't work for images with multiple frames.
     if (m_frameBufferCache.isEmpty()) {
-      m_frameBufferCache.resize(1);
-      m_frameBufferCache[0].setRequiredPreviousFrameIndex(
-          findRequiredPreviousFrame(0, false));
+      // Ensure that initializeNewFrame is called, after parsing if
+      // necessary.
+      if (!frameCount())
+        return;
     }
+
     m_frameBufferCache[0].setMemoryAllocator(allocator);
   }
 
@@ -313,9 +315,11 @@ class PLATFORM_EXPORT ImageDecoder {
   virtual size_t decodeFrameCount() { return 1; }
 
   // Called to initialize the frame buffer with the given index, based on the
-  // provided and previous frame's characteristics. Returns true on success. On
-  // failure, this will mark the image as failed. Before calling this method,
-  // the caller must verify that the frame exists.
+  // provided and previous frame's characteristics. Returns true on success.
+  // Before calling this method, the caller must verify that the frame exists.
+  // On failure, the client should call setFailed. This method does not call
+  // setFailed itself because that might delete the object directly making this
+  // call.
   bool initFrameBuffer(size_t);
 
   // Performs any additional setup of the requested frame after it has been