Allow eviction of ImageBitmaps that are created from ImageElements.

Source/core/loader/cache/Resource.h

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller <mueller@kde.org>
     Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
     Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 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 66 matching lines @@
         Unknown, // let cache decide what to do with it
         Pending, // only partially loaded
         Cached, // regular case
         LoadError,
         DecodeError
     };
 
     Resource(const ResourceRequest&, Type);
     virtual ~Resource();
 
+    // Determines the order in which CachedResources are evicted
+    // from the decoded resources cache.
+    enum CacheLiveResourcePriority {
+        CacheLiveResourcePriorityLow = 0,
+        CacheLiveResourcePriorityHigh
+    };
+
     virtual void load(ResourceFetcher*, const ResourceLoaderOptions&);
 
     virtual void setEncoding(const String&) { }
     virtual String encoding() const { return String(); }
     virtual void appendData(const char*, int);
     virtual void error(Resource::Status);
 
     void setResourceError(const ResourceError& error) { m_error = error; }
     const ResourceError& resourceError() const { return m_error; }
 
@@ skipping 64 matching lines @@
     bool passesAccessControlCheck(SecurityOrigin*);
     bool passesAccessControlCheck(SecurityOrigin*, String& errorDescription);
 
     // Called by the cache if the object has been removed from the cache
     // while still being referenced. This means the object should delete itself
     // if the number of clients observing it ever drops to 0.
     // The resource can be brought back to cache after successful revalidation.
     void setInCache(bool inCache) { m_inCache = inCache; }
     bool inCache() const { return m_inCache; }
 
+    void setCacheLiveResourcePriority(CacheLiveResourcePriority);
+    unsigned cacheLiveResourcePriority() const { return m_cacheLiveResourcePriority; }
     bool inLiveDecodedResourcesList() { return m_inLiveDecodedResourcesList; }
 
     void clearLoader();
 
     SharedBuffer* resourceBuffer() const { ASSERT(!m_purgeableData); return m_data.get(); }
 
     virtual void willSendRequest(ResourceRequest&, const ResourceResponse&) { m_requestedFromNetworkingLayer = true; }
     virtual void responseReceived(const ResourceResponse&);
     void setResponse(const ResourceResponse& response) { m_response = response; }
     const ResourceResponse& response() const { return m_response; }
@@ skipping 123 matching lines @@
 
     unsigned long m_identifier;
 
     unsigned m_encodedSize;
     unsigned m_decodedSize;
     unsigned m_accessCount;
     unsigned m_handleCount;
     unsigned m_preloadCount;
 
     unsigned m_preloadResult : 2; // PreloadResult
-
+    unsigned m_cacheLiveResourcePriority : 2; // CacheLiveResourcePriority
     unsigned m_inLiveDecodedResourcesList : 1;
     unsigned m_requestedFromNetworkingLayer : 1;
 
     unsigned m_inCache : 1;
     unsigned m_loading : 1;
 
     unsigned m_switchingClientsToRevalidatedResource : 1;
 
     unsigned m_type : 4; // Type
     unsigned m_status : 3; // Status
@@ skipping 18 matching lines @@
     // If this field is non-null, the resource has a proxy for checking whether it is still up to date (see m_resourceToRevalidate).
     Resource* m_proxyResource;
 
     // These handles will need to be updated to point to the m_resourceToRevalidate in case we get 304 response.
     HashSet<ResourcePtrBase*> m_handlesToRevalidate;
 };
 
 }
 
 #endif