Make MemoryCache::contains() take a const Resource pointer.

Source/core/fetch/MemoryCache.cpp

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller (mueller@kde.org)
     Copyright (C) 2002 Waldo Bastian (bastian@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 106 matching lines @@
 }
 
 void MemoryCache::replace(Resource* newResource, Resource* oldResource)
 {
     evict(oldResource);
     add(newResource);
     if (newResource->decodedSize() && newResource->hasClients())
         insertInLiveDecodedResourcesList(newResource);
 }
 
-bool MemoryCache::contains(Resource* resource)
+bool MemoryCache::contains(const Resource* resource) const
 {
     if (resource->url().isNull())
         return false;
-    MemoryCacheEntry* entry = m_resources.get(resource->url());
+    const MemoryCacheEntry* entry = m_resources.get(resource->url());
     return entry && entry->m_resource == resource;
 }
 
 Resource* MemoryCache::resourceForURL(const KURL& resourceURL)
 {
     ASSERT(WTF::isMainThread());
     KURL url = removeFragmentIdentifierIfNeeded(resourceURL);
     MemoryCacheEntry* entry = m_resources.get(url);
     if (!entry)
         return 0;
@@ skipping 531 matching lines @@
                 printf("(%.1fK, %.1fK, %uA, %dR, %d, %d); ", current->decodedSize() / 1024.0f, (current->encodedSize() + current->overheadSize()) / 1024.0f, current->accessCount(), current->hasClients(), current->isPurgeable(), current->wasPurged());
 
             current = prev;
         }
     }
 }
 
 #endif // MEMORY_CACHE_STATS
 
 } // namespace WebCore