Move GIF decoder's aggressive purge into ImageDecoder

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

Index: third_party/WebKit/Source/platform/image-decoders/gif/GIFImageDecoder.cpp
diff --git a/third_party/WebKit/Source/platform/image-decoders/gif/GIFImageDecoder.cpp b/third_party/WebKit/Source/platform/image-decoders/gif/GIFImageDecoder.cpp
index ba4cca2bb13c8da2bcc7cbc66cdad6fd869999b3..32cc3e56a6e5ea948bcaba2bef99da49d7cd70a0 100644
--- a/third_party/WebKit/Source/platform/image-decoders/gif/GIFImageDecoder.cpp
+++ b/third_party/WebKit/Source/platform/image-decoders/gif/GIFImageDecoder.cpp
@@ -34,7 +34,6 @@ namespace blink {
 
 GIFImageDecoder::GIFImageDecoder(AlphaOption alphaOption, GammaAndColorProfileOption colorOptions, size_t maxDecodedBytes)
     : ImageDecoder(alphaOption, colorOptions, maxDecodedBytes)
-    , m_purgeAggressively(false)
     , m_repetitionCount(cAnimationLoopOnce)
 {
 }
@@ -382,48 +381,4 @@ bool GIFImageDecoder::initFrameBuffer(size_t frameIndex)
     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