Fix null dereference on MemoryCache.

third_party/WebKit/Source/core/fetch/MemoryCache.h

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller <mueller@kde.org>
     Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
 
     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Library General Public
     License as published by the Free Software Foundation; either
     version 2 of the License, or (at your option) any later version.
 
@@ skipping 219 matching lines @@
     void willProcessTask() override;
     void didProcessTask() override;
 
     void pruneAll();
 
     void updateFramePaintTimestamp();
 
     // Take memory usage snapshot for tracing.
     void onMemoryDump(WebMemoryDumpLevelOfDetail, WebProcessMemoryDump*);
 
+    bool isInSameLRUListForTest(const Resource*, const Resource*);
 private:
     enum PruneStrategy {
         // Automatically decide how much to prune.
         AutomaticPrune,
         // Maximally prune resources.
         MaximalPrune
     };
 
     MemoryCache();
 
@@ skipping 79 matching lines @@
 // Returns the global cache.
 CORE_EXPORT MemoryCache* memoryCache();
 
 // Sets the global cache, used to swap in a test instance. Returns the old
 // MemoryCache object.
 CORE_EXPORT MemoryCache* replaceMemoryCacheForTesting(MemoryCache*);
 
 }
 
 #endif