GIF Animations "clear from cache related glitch" fix

third_party/WebKit/Source/platform/image-decoders/ImageDecoder.h

Index: third_party/WebKit/Source/platform/image-decoders/ImageDecoder.h
diff --git a/third_party/WebKit/Source/platform/image-decoders/ImageDecoder.h b/third_party/WebKit/Source/platform/image-decoders/ImageDecoder.h
index 2ebd7797caf99844abc34018d95e42f885f8b453..fd0fbd7d66d8726aa59f18658ff558163947d22e 100644
--- a/third_party/WebKit/Source/platform/image-decoders/ImageDecoder.h
+++ b/third_party/WebKit/Source/platform/image-decoders/ImageDecoder.h
@@ -35,6 +35,7 @@
 #include "platform/image-decoders/ImageFrame.h"
 #include "public/platform/Platform.h"
 #include "wtf/Assertions.h"
+#include "wtf/HashSet.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/RefPtr.h"
 #include "wtf/Threading.h"
@@ -46,6 +47,7 @@
 #endif
 
 typedef Vector<char> ColorProfile;
+typedef HashSet<size_t, WTF::IntHash<size_t>, WTF::UnsignedWithZeroKeyHashTraits<size_t>> SizeTHashSet;
 
 namespace blink {
 
@@ -334,6 +336,12 @@ protected:
     // Decodes the requested frame.
     virtual void decode(size_t) = 0;
 
+    // Clears decoded pixel data from all frames except the provided frames.
+    // Callers may pass WTF::kNotFound to clear all frames.
+    // Note: If |m_frameBufferCache| contains only one frame, it won't be cleared.
+    // Returns the number of bytes of frame data actually cleared.
+    size_t clearCacheExceptFrames(const SizeTHashSet&);
+
     RefPtr<SharedBuffer> m_data; // The encoded data.
     Vector<ImageFrame, 1> m_frameBufferCache;
     bool m_premultiplyAlpha;