Don't cache GIF frames if it would be too large.

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

Index: third_party/WebKit/Source/platform/image-decoders/gif/GIFImageDecoder.h
diff --git a/third_party/WebKit/Source/platform/image-decoders/gif/GIFImageDecoder.h b/third_party/WebKit/Source/platform/image-decoders/gif/GIFImageDecoder.h
index a2c6ce1185ce92dc4a858cae8080da6177d3bc3c..d5f8b57c213b0bab6674bc6df0b2afdb46ec1d11 100644
--- a/third_party/WebKit/Source/platform/image-decoders/gif/GIFImageDecoder.h
+++ b/third_party/WebKit/Source/platform/image-decoders/gif/GIFImageDecoder.h
@@ -84,7 +84,10 @@ private:
     // Like clearCacheExceptFrame(), but preserves two frames instead of one.
     size_t clearCacheExceptTwoFrames(size_t, size_t);
 
+    void updateAggressivePurging(size_t index);
+
     bool m_currentBufferSawAlpha;
+    bool m_purgeAggressively;
     mutable int m_repetitionCount;
     std::unique_ptr<GIFImageReader> m_reader;
 };