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

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

Index: third_party/WebKit/Source/platform/image-decoders/webp/WEBPImageDecoder.cpp
diff --git a/third_party/WebKit/Source/platform/image-decoders/webp/WEBPImageDecoder.cpp b/third_party/WebKit/Source/platform/image-decoders/webp/WEBPImageDecoder.cpp
index 2672862d85e13b5b65612075ffccf1ef424f6463..858f05c3b62cc628fb77aa8f56c3419d3cb7ad4e 100644
--- a/third_party/WebKit/Source/platform/image-decoders/webp/WEBPImageDecoder.cpp
+++ b/third_party/WebKit/Source/platform/image-decoders/webp/WEBPImageDecoder.cpp
@@ -165,12 +165,12 @@ int WEBPImageDecoder::repetitionCount() const
     return failed() ? cAnimationLoopOnce : m_repetitionCount;
 }
 
-bool WEBPImageDecoder::frameIsCompleteAtIndex(size_t index) const
+bool WEBPImageDecoder::frameIsFullyReceivedAtIndex(size_t index) const

[Peter Kasting, 2016/05/10 00:00:13]

I'm not convinced this function is correct for frameIsFullyReceivedAtIndex(). 
It looks like for animated images it implements something closer to
frameIsCompleteAtIndex() instead.

[aleksandar.stojiljkovic, 2016/05/10 21:59:31]

I briefly checked  WEBPImageDecoder::decodeFrameCount() and updateDemuxer.
decodeFrameCount() is used to update m_frameBufferCache.size()and
decodeFrameCount is based on frames that are already received. Don't know - it
looks correct to me but will debug it first.

In this change I don't think it matters - WEBP is multiframe decoder as GIF and
frameIsCompleteAtIndex is for the same use cases just renamed to
frameIsFullyReceivedAtIndex (it is renamed but functionality is the same).

[scroggo_chromium, 2016/05/11 15:17:34]

As I understand it, GIF's version of frameIsFullyReceivedAtIndex tells us that
we have received all the bytes for a frame (assuming it's valid). So if we
decode that frame (maybe we haven't yet) it will end up as FrameComplete without
providing more data (again, assuming it's valid).

Looking at WEBP's decodeFrameCount, it is not obvious that we have received
enough data to mark the frame FrameComplete after a decode.

 {
     if (!m_demux || m_demuxState <= WEBP_DEMUX_PARSING_HEADER)
         return false;
     if (!(m_formatFlags & ANIMATION_FLAG))
-        return ImageDecoder::frameIsCompleteAtIndex(index);
+        return ImageDecoder::frameIsFullyReceivedAtIndex(index);
     bool frameIsLoadedAtIndex = index < m_frameBufferCache.size();
     return frameIsLoadedAtIndex;
 }
@@ -495,7 +495,7 @@ bool WEBPImageDecoder::decodeSingleFrame(const uint8_t* dataBytes, size_t dataSi
         clearDecoder();
         return true;
     case VP8_STATUS_SUSPENDED:
-        if (!isAllDataReceived() && !frameIsCompleteAtIndex(frameIndex)) {
+        if (!isAllDataReceived() && !frameIsFullyReceivedAtIndex(frameIndex)) {
             applyPostProcessing(frameIndex);
             return false;
         }