Checking if frame is complete and access duration doesn't need a decode

Source/core/platform/image-decoders/ImageDecoder.h

Index: Source/core/platform/image-decoders/ImageDecoder.h
diff --git a/Source/core/platform/image-decoders/ImageDecoder.h b/Source/core/platform/image-decoders/ImageDecoder.h
index a5dab7944f45c872daa5d0ea27132c8151e73dae..da00a95275516b8ffadb16f17deba2896d0fd33b 100644
--- a/Source/core/platform/image-decoders/ImageDecoder.h
+++ b/Source/core/platform/image-decoders/ImageDecoder.h
@@ -293,6 +293,12 @@ namespace WebCore {
         // Make the best effort guess to check if the requested frame has alpha channel.
         virtual bool frameHasAlphaAtIndex(size_t) const;
 
+        // Whether or not the frame is fully received.
+        virtual bool frameIsCompleteAtIndex(size_t) const;
+
+        // Duration for displaying a frame in seconds. This method is used by animated images only.
+        virtual float frameDurationAtIndex(size_t) const { return 0; }
+
         // Number of bytes in the decoded frame requested. Return 0 if not yet decoded.
         virtual unsigned frameBytesAtIndex(size_t) const;