Add UMA to track time between preload discovery and reference

third_party/WebKit/Source/core/fetch/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 89 matching lines @@
     virtual String encoding() const { return String(); }
     virtual void appendData(const char*, size_t);
     virtual void error(const ResourceError&);
     virtual void setCORSFailed() { }
 
     void setNeedsSynchronousCacheHit(bool needsSynchronousCacheHit) { m_needsSynchronousCacheHit = needsSynchronousCacheHit; }
 
     void setLinkPreload(bool isLinkPreload) { m_linkPreload = isLinkPreload; }
     bool isLinkPreload() const { return m_linkPreload; }
 
+    void setPreloadDiscoveryTime(double preloadDiscoveryTime) { m_preloadDiscoveryTime = preloadDiscoveryTime; }
+
     const ResourceError& resourceError() const { return m_error; }
 
     void setIdentifier(unsigned long identifier) { m_identifier = identifier; }
     unsigned long identifier() const { return m_identifier; }
 
     virtual bool shouldIgnoreHTTPStatusCodeErrors() const { return false; }
 
     const ResourceRequest& resourceRequest() const { return m_resourceRequest; }
     const ResourceRequest& lastResourceRequest() const;
 
@@ skipping 210 matching lines @@
     size_t m_decodedSize;
 
     // Resource::calculateOverheadSize() is affected by changes in
     // |m_resourceRequest.url()|, but |m_overheadSize| is not updated after
     // initial |m_resourceRequest| is given, to reduce MemoryCache manipulation
     // and thus potential bugs. crbug.com/594644
     const size_t m_overheadSize;
 
     unsigned m_preloadCount;
 
+    double m_preloadDiscoveryTime;
+
     String m_cacheIdentifier;
 
     unsigned m_preloadResult : 2; // PreloadResult
     unsigned m_type : 4; // Type
     unsigned m_status : 3; // Status
 
     unsigned m_needsSynchronousCacheHit : 1;
     unsigned m_linkPreload : 1;
 
     // Ordered list of all redirects followed while fetching this resource.
@@ skipping 11 matching lines @@
 
     Resource::Type m_type;
 };
 
 #define DEFINE_RESOURCE_TYPE_CASTS(typeName) \
     DEFINE_TYPE_CASTS(typeName##Resource, Resource, resource, resource->getType() == Resource::typeName, resource.getType() == Resource::typeName);
 
 } // namespace blink
 
 #endif