MemoryCache: Enable MemoryCache to have multiple isolated resource maps

Source/core/fetch/Resource.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 88 matching lines @@
     : m_resourceRequest(request)
     , m_responseTimestamp(currentTime())
     , m_cancelTimer(this, &Resource::cancelTimerFired)
     , m_loadFinishTime(0)
     , m_identifier(0)
     , m_encodedSize(0)
     , m_decodedSize(0)
     , m_handleCount(0)
     , m_preloadCount(0)
     , m_protectorCount(0)
+    , m_cacheIdentifier(MemoryCache::defaultCacheIdentifier())
     , m_preloadResult(PreloadNotReferenced)
     , m_requestedFromNetworkingLayer(false)
     , m_loading(false)
     , m_switchingClientsToRevalidatedResource(false)
     , m_type(type)
     , m_status(Pending)
     , m_wasPurged(false)
     , m_needsSynchronousCacheHit(false)
 #ifdef ENABLE_RESOURCE_IS_DELETED_CHECK
     , m_deleted(false)
@@ skipping 16 matching lines @@
     m_fragmentIdentifierForRequest = m_resourceRequest.url().fragmentIdentifier();
     m_resourceRequest.setURL(urlForCache);
 }
 
 Resource::~Resource()
 {
     ASSERT(!m_resourceToRevalidate); // Should be true because canDelete() checks this.
     ASSERT(canDelete());
     RELEASE_ASSERT(!memoryCache()->contains(this));
     RELEASE_ASSERT(!ResourceCallback::callbackHandler()->isScheduled(this));
-    ASSERT(url().isNull() || memoryCache()->resourceForURL(KURL(ParsedURLString, url())) != this);

[Mike West, 2014/10/24 12:43:00]

Why is it safe to drop this ASSERT?

[nhiroki, 2014/10/27 14:30:13]

This case would be covered by ASSERT(!memoryCache()->contains(this)) at line 143

     assertAlive();
 
 #ifdef ENABLE_RESOURCE_IS_DELETED_CHECK
     m_deleted = true;
 #endif
 #ifndef NDEBUG
     cachedResourceLeakCounter.decrement();
 #endif
     --s_instanceCount;
 }
@@ skipping 851 matching lines @@
         return "ImportResource";
     case Resource::Media:
         return "Media";
     }
     ASSERT_NOT_REACHED();
     return "Unknown";
 }
 #endif // !LOG_DISABLED
 
 }