Clear ResourceFetcher::m_validatedURLs if too many entries are added

Source/core/fetch/ResourceFetcher.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, 2009, 2010, 2011 Apple Inc. All rights reserved.
     Copyright (C) 2009 Torch Mobile Inc. http://www.torchmobile.com/
 
     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 188 matching lines @@
 
     void garbageCollectDocumentResourcesTimerFired(Timer<ResourceFetcher>*);
     void scheduleDocumentResourcesGC();
 
     void resourceTimingReportTimerFired(Timer<ResourceFetcher>*);
 
     bool clientDefersImage(const KURL&) const;
     void reloadImagesIfNotDeferred();
 
     HashSet<String> m_validatedURLs;
+    Deque<String> m_validatedURLsRingBuffer;

[kouhei (in TOK), 2014/11/14 09:15:57]

My bad. I didn't notice m_validatedURLs was a HashSet.
If we could use base/, we could use MRUCache here, but no access to base/ is
allowed yet.

     mutable DocumentResourceMap m_documentResources;
     // FIXME: Oilpan: Ideally this should just be a traced Member but that will
     // currently leak because RenderStyle and its data are not on the heap.
     // See crbug.com/383860 for details.
     RawPtrWillBeWeakMember<Document> m_document;
     DocumentLoader* m_documentLoader;
 
     int m_requestCount;
 
     OwnPtr<ListHashSet<Resource*>> m_preloads;
@@ skipping 49 matching lines @@
             m_loader->m_allowStaleResources = m_previousState;
     }
 private:
     ResourceFetcher* m_loader;
     bool m_previousState;
 };
 
 } // namespace blink
 
 #endif