Fix ImageDecoder::frameIsCompleteAtIndex - fully received instead of decoded.

third_party/WebKit/Source/platform/image-decoders/webp/WEBPImageDecoder.cpp

 /*
  * Copyright (C) 2010 Google 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 148 matching lines @@
 void WEBPImageDecoder::onSetData(SegmentReader*)
 {
     m_haveAlreadyParsedThisData = false;
 }
 
 int WEBPImageDecoder::repetitionCount() const
 {
     return failed() ? cAnimationLoopOnce : m_repetitionCount;
 }
 
-bool WEBPImageDecoder::frameIsCompleteAtIndex(size_t index) const
+bool WEBPImageDecoder::frameIsFullyReceivedAtIndex(size_t index) const
 {
-    if (!m_demux || m_demuxState <= WEBP_DEMUX_PARSING_HEADER)
-        return false;
     if (!(m_formatFlags & ANIMATION_FLAG))
-        return ImageDecoder::frameIsCompleteAtIndex(index);
-    bool frameIsLoadedAtIndex = index < m_frameBufferCache.size();
-    return frameIsLoadedAtIndex;
+        return ImageDecoder::frameIsFullyReceivedAtIndex(index) || frameIsCompleteAtIndex(index);

[scroggo_chromium, 2016/05/24 13:55:14]

Do you need "|| frameIsCompleteAtIndex(index)"? Is it possible that the frame is
marked as complete if frameIsFullyReceivedAtIndex returned false?

Is this the case where the frame got marked complete before we received the last
two bytes?

Another question that might be relevant - does the caller need to know
frameIsCompleteAtIndex? The main caller of (the newly named)
frameIsFullyReceivedAtIndex is DeferredImageDecoder, which calls it on
m_actualDecoder, where frameIsCompleteAtIndex will never be true. But I think
that's fine, because it really wants to know whether the frame is fully
received.

[aleksandar.stojiljkovic, 2016/05/24 19:24:34]

Yes, that is exactly the case. WebP parsing doesn't mark the frame as complete
but when we decode it we get complete frame. WebP parsing marks it as complete 2
bytes later. So I added the "|| frameIsCompleteAtIndex(index);" to cover it.
As it can happen only in tests, no point in having the check. Removed it.

+    return index < m_frameBufferCache.size() || failed();
 }
 
 float WEBPImageDecoder::frameDurationAtIndex(size_t index) const
 {
     return index < m_frameBufferCache.size() ? m_frameBufferCache[index].duration() : 0;
 }
 
 bool WEBPImageDecoder::updateDemuxer()
 {
     if (failed())
@@ skipping 318 matching lines @@
             return false;
         }
         // FALLTHROUGH
     default:
         clear();
         return setFailed();
     }
 }
 
 } // namespace blink