Cap memory usage in webp catch up

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 217 matching lines @@
   ASSERT(m_demuxState > WEBP_DEMUX_PARSING_HEADER);
   if (!WebPDemuxGetI(m_demux, WEBP_FF_FRAME_COUNT))
     return false;  // Wait until the encoded image frame data arrives.
 
   if (!isDecodedSizeAvailable()) {
     int width = WebPDemuxGetI(m_demux, WEBP_FF_CANVAS_WIDTH);
     int height = WebPDemuxGetI(m_demux, WEBP_FF_CANVAS_HEIGHT);
     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;
     } else {
       // Since we have parsed at least one frame, even if partially,
       // the global animation (ANIM) properties have been read since
       // an ANIM chunk must precede the ANMF frame chunks.
       m_repetitionCount = WebPDemuxGetI(m_demux, WEBP_FF_LOOP_COUNT);
       // Repetition count is always <= 16 bits.
       ASSERT(m_repetitionCount == (m_repetitionCount & 0xffff));
@@ skipping 231 matching lines @@
     } else {
       decodeSingleFrame(webpFrame.fragment.bytes, webpFrame.fragment.size, *i);
       WebPDemuxReleaseIterator(&webpFrame);
     }
     if (failed())
       return;
 
     // 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
   // frames available but the file is truncated.
   if (index >= m_frameBufferCache.size() - 1 && isAllDataReceived() &&
       m_demux && m_demuxState != WEBP_DEMUX_DONE)
     setFailed();
 }
 
 bool WEBPImageDecoder::decodeSingleFrame(const uint8_t* dataBytes,
@@ skipping 58 matching lines @@
         return false;
       }
     // FALLTHROUGH
     default:
       clear();
       return setFailed();
   }
 }
 
 }  // namespace blink