Move GIF decoder's aggressive purge into ImageDecoder

third_party/WebKit/Source/platform/image-decoders/gif/GIFImageDecoder.cpp

 /*
  * Copyright (C) 2006 Apple Computer, 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 16 matching lines @@
 
 #include "platform/image-decoders/gif/GIFImageReader.h"
 #include "wtf/NotFound.h"
 #include "wtf/PtrUtil.h"
 #include <limits>
 
 namespace blink {
 
 GIFImageDecoder::GIFImageDecoder(AlphaOption alphaOption, GammaAndColorProfileOption colorOptions, size_t maxDecodedBytes)
     : ImageDecoder(alphaOption, colorOptions, maxDecodedBytes)
-    , m_purgeAggressively(false)
     , m_repetitionCount(cAnimationLoopOnce)
 {
 }
 
 GIFImageDecoder::~GIFImageDecoder()
 {
 }
 
 void GIFImageDecoder::onSetData(SegmentReader* data)
 {
@@ skipping 327 matching lines @@
         }
     }
 
     // Update our status to be partially complete.
     buffer->setStatus(ImageFrame::FramePartial);
 
     // Reset the alpha pixel tracker for this frame.
     m_currentBufferSawAlpha = false;
     return true;
 }
-
-void GIFImageDecoder::updateAggressivePurging(size_t index)
-{
-    if (m_purgeAggressively)
-        return;
-
-    // We don't want to cache so much that we cause a memory issue.
-    //
-    // If we used a LRU cache we would fill it and then on next animation loop
-    // we would need to decode all the frames again -- the LRU would give no
-    // benefit and would consume more memory.
-    // So instead, simply purge unused frames if caching all of the frames of
-    // the image would use more memory than the image decoder is allowed
-    // (m_maxDecodedBytes) or would overflow 32 bits..
-    //
-    // As we decode we will learn the total number of frames, and thus total
-    // possible image memory used.
-
-    const uint64_t frameArea = decodedSize().area();
-    // We are about to multiply by 4, which may require an extra bit of storage
-    bool wouldOverflow = frameArea > (UINT64_C(1) << 62);
-    if (wouldOverflow) {
-        m_purgeAggressively = true;
-        return;
-    }
-
-    const uint64_t frameMemoryUsage = frameArea * 4; // 4 bytes per pixel
-    // We are about to multiply by a size_t, which does not have a fixed
-    // size.
-    // To simplify things, let's make sure our per-frame memory usage and
-    // index can be stored in 32 bits and store the multiplicand in a 64-bit
-    // number.
-    wouldOverflow = (frameMemoryUsage > (UINT32_C(1) << 31))
-        || (index > (UINT32_C(1) << 31));
-    if (wouldOverflow) {
-        m_purgeAggressively = true;
-        return;
-    }
-
-    const uint64_t totalMemoryUsage = frameMemoryUsage * index;
-    if (totalMemoryUsage > m_maxDecodedBytes) {
-        m_purgeAggressively = true;
-    }
-}
 } // namespace blink