MemoryCache: Enable MemoryCache to have multiple isolated resource maps

Source/core/fetch/CachingCorrectnessTest.cpp

 /*
  * Copyright (c) 2014, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 442 matching lines @@
     request1.setHTTPMethod("POST");
     ResourcePtr<Resource> resource1 = new Resource(ResourceRequest(request1.url()), Resource::Raw);
     resource1->setLoading(true);
     memoryCache()->add(resource1.get());
 
     ResourceRequest request2(KURL(ParsedURLString, kResourceURL));
     request2.setHTTPMethod("POST");
     FetchRequest fetch2(request2, FetchInitiatorInfo());
     ResourcePtr<Resource> resource2 = fetcher()->fetchSynchronously(fetch2);
 
-    EXPECT_EQ(resource2, memoryCache()->resourceForURL(request2.url()));
+    EXPECT_EQ(resource2, memoryCache()->resourceForURL(MemoryCache::defaultCacheIdentifier(), request2.url()));
     EXPECT_NE(resource1, resource2);
 }
 
 TEST_F(CachingCorrectnessTest, 302RedirectNotImplicitlyFresh)
 {
     KURL redirectUrl(ParsedURLString, kResourceURL);
     const char redirectTargetUrlString[] = "http://redirect-target.com";
     KURL redirectTargetUrl(ParsedURLString, redirectTargetUrlString);
 
     ResourcePtr<Resource> firstResource = new Resource(ResourceRequest(redirectUrl), Resource::Raw);
@@ skipping 89 matching lines @@
     firstResource->setResponse(fresh200Response);
     memoryCache()->add(firstResource.get());
 
     advanceClock(500.);
 
     ResourcePtr<Resource> fetched = fetch();
     EXPECT_EQ(firstResource, fetched);
 }
 
 } // namespace