Cap memory usage in webp catch up

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 914def5256a8fb57e0b10d6391df3ad6771b1441..04f77db320d55bf62352fec3ffcc6ac3d5fa99f5 100644
--- a/third_party/WebKit/Source/platform/image-decoders/webp/WEBPImageDecoder.cpp
+++ b/third_party/WebKit/Source/platform/image-decoders/webp/WEBPImageDecoder.cpp
@@ -235,6 +235,9 @@ bool WEBPImageDecoder::updateDemuxer() {
     if (!setSize(width, height))
       return setFailed();
 
+    size_t frameCount = WebPDemuxGetI(m_demux, WEBP_FF_FRAME_COUNT);

[urvang, 2016/10/10 21:30:50]

No, this is not the right place. "!isDecodedSizeAvailable()" would be true only
once for an image, because overall width/height of an image comes at the
beginning of a WebP file. (Note: this is the canvas width/height, and not that
of a given frame).

So, this logic happen unconditionally, and so, it should go at the end of
updateDemuxer() (just before "return true").

[cblume, 2016/10/10 21:36:38]

Done.

+    updateAggressivePurging(frameCount);
+
     m_formatFlags = WebPDemuxGetI(m_demux, WEBP_FF_FORMAT_FLAGS);
     if (!(m_formatFlags & ANIMATION_FLAG)) {
       m_repetitionCount = cAnimationNone;
@@ -486,6 +489,9 @@ void WEBPImageDecoder::decode(size_t index) {
     // We need more data to continue decoding.
     if (m_frameBufferCache[*i].getStatus() != ImageFrame::FrameComplete)
       break;
+
+    if (m_purgeAggressively)
+      clearCacheExceptFrame(*i);
   }
 
   // It is also a fatal error if all data is received and we have decoded all