Add UMA to track time between preload discovery and reference

third_party/WebKit/Source/core/fetch/ResourceFetcher.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, 2009, 2010, 2011 Apple Inc. All rights reserved.
     Copyright (C) 2009 Torch Mobile Inc. http://www.torchmobile.com/
 
     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 552 matching lines @@
 
 Resource* ResourceFetcher::createResourceForLoading(FetchRequest& request, const String& charset, const ResourceFactory& factory)
 {
     const String cacheIdentifier = getCacheIdentifier();
     ASSERT(!memoryCache()->resourceForURL(request.resourceRequest().url(), cacheIdentifier));
 
     WTF_LOG(ResourceLoading, "Loading Resource for '%s'.", request.resourceRequest().url().elidedString().latin1().data());
 
     Resource* resource = factory.create(request.resourceRequest(), request.options(), charset);
     resource->setLinkPreload(request.isLinkPreload());
+    if (request.forPreload()) {
+        resource->setPreloadDiscoveryTime(request.preloadDiscoveryTime());
+    }
     resource->setCacheIdentifier(cacheIdentifier);
 
     // Don't add main resource to cache to prevent reuse.
     if (factory.type() != Resource::MainResource)
         memoryCache()->add(resource);
     return resource;
 }
 
 void ResourceFetcher::storeResourceTimingInitiatorInformation(Resource* resource)
 {
@@ skipping 633 matching lines @@
     visitor->trace(m_context);
     visitor->trace(m_archive);
     visitor->trace(m_loaders);
     visitor->trace(m_nonBlockingLoaders);
     visitor->trace(m_documentResources);
     visitor->trace(m_preloads);
     visitor->trace(m_resourceTimingInfoMap);
 }
 
 } // namespace blink