blink: Fix frame completion querying for static images.

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

Index: third_party/WebKit/Source/platform/image-decoders/ImageDecoder.cpp
diff --git a/third_party/WebKit/Source/platform/image-decoders/ImageDecoder.cpp b/third_party/WebKit/Source/platform/image-decoders/ImageDecoder.cpp
index e7eac4b4a3f696ab1f6871dafc99fab7d4d1b4e3..f0b4ed856c6d5f048a0c8449db94856ba2325ba8 100644
--- a/third_party/WebKit/Source/platform/image-decoders/ImageDecoder.cpp
+++ b/third_party/WebKit/Source/platform/image-decoders/ImageDecoder.cpp
@@ -182,13 +182,19 @@ ImageFrame* ImageDecoder::FrameBufferAtIndex(size_t index) {
 }
 
 bool ImageDecoder::FrameHasAlphaAtIndex(size_t index) const {
-  return !FrameIsCompleteAtIndex(index) ||
+  return index < frame_buffer_cache_.size() &&

[urvang, 2017/05/15 17:33:07]

Shouldn't you call "FrameIsDecodedAtIndex()" now instead?

[Khushal, 2017/05/15 17:55:17]

FrameIsDecodedAtIndex is true only if the decoded data for that frame is cached.
For the cases where the decoder is used just for reading the metadata on the
main thread, this will never be true. From a quick glance, it looks like the
only code that uses it is that exact case in DeferredImageDecoder.

I can just keep the current call FrameIsCompleteAtIndex here to avoid a change
in behaviour?

[urvang, 2017/05/15 18:02:10]

Yes, if keeping the current call still works, you can do this change separately.

[Khushal, 2017/05/15 20:44:48]

Done.

          frame_buffer_cache_[index].HasAlpha();
 }
 
 bool ImageDecoder::FrameIsCompleteAtIndex(size_t index) const {
-  return (index < frame_buffer_cache_.size()) &&
-         (frame_buffer_cache_[index].GetStatus() == ImageFrame::kFrameComplete);
+  // Animated images override this method to return the status based on the data
+  // received for the queried frame.
+  return IsAllDataReceived();

[urvang, 2017/05/15 17:33:07]

I'm curious if you get a warning about "index" being unused here. 

[Khushal, 2017/05/15 17:55:17]

The bots don't seem to be complaining.

[urvang, 2017/05/15 18:02:10]

Acknowledged.

+}
+
+bool ImageDecoder::FrameIsDecodedAtIndex(size_t index) const {
+  return index < frame_buffer_cache_.size() &&
+         frame_buffer_cache_[index].GetStatus() == ImageFrame::kFrameComplete;
 }
 
 size_t ImageDecoder::FrameBytesAtIndex(size_t index) const {