Allow eviction of ImageBitmaps that are created from ImageElements.

Source/core/loader/cache/CachedResource.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) 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
@@ skipping 87 matching lines @@
     }
     for (size_t i = 0; i < WTF_ARRAY_LENGTH(headerPrefixesToIgnoreAfterRevalidation); i++) {
         if (header.startsWith(headerPrefixesToIgnoreAfterRevalidation[i]))
             return false;
     }
     return true;
 }
 
 DEFINE_DEBUG_ONLY_GLOBAL(RefCountedLeakCounter, cachedResourceLeakCounter, ("CachedResource"));
 
-CachedResource::CachedResource(const ResourceRequest& request, Type type)
+CachedResource::CachedResource(const ResourceRequest& request, Type type, DecodeCachePriority decodeCachePriority)

[Justin Novosad, 2013/07/19 21:09:53]

No need for extra construction arg. Just initialize with low priority by
default. Client code can raise priority explicitly if needed.

     : m_resourceRequest(request)
     , m_responseTimestamp(currentTime())
     , m_decodedDataDeletionTimer(this, &CachedResource::decodedDataDeletionTimerFired)
     , m_cancelTimer(this, &CachedResource::cancelTimerFired)
     , m_lastDecodedAccessTime(0)
     , m_loadFinishTime(0)
     , m_identifier(0)
     , m_encodedSize(0)
     , m_decodedSize(0)
     , m_accessCount(0)
     , m_handleCount(0)
     , m_preloadCount(0)
     , m_preloadResult(PreloadNotReferenced)
+    , m_decodeCachePriority(decodeCachePriority)
     , m_inLiveDecodedResourcesList(false)
     , m_requestedFromNetworkingLayer(false)
     , m_inCache(false)
     , m_loading(false)
     , m_switchingClientsToRevalidatedResource(false)
     , m_type(type)
     , m_status(Pending)
 #ifndef NDEBUG
     , m_deleted(false)
     , m_lruIndex(0)
@@ skipping 742 matching lines @@
     info.addMember(m_proxyResource, "proxyResource");
     info.addMember(m_handlesToRevalidate, "handlesToRevalidate");
     info.addMember(m_options, "options");
     info.addMember(m_decodedDataDeletionTimer, "decodedDataDeletionTimer");
     info.ignoreMember(m_clientsAwaitingCallback);
 
     if (m_purgeableData && !m_purgeableData->wasPurged())
         info.addRawBuffer(m_purgeableData.get(), m_purgeableData->size(), "PurgeableData", "purgeableData");
 }
 }
+