[NoStatePrefetch] Add performance histograms.

chrome/browser/page_load_metrics/metrics_web_contents_observer.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_PAGE_LOAD_METRICS_METRICS_WEB_CONTENTS_OBSERVER_H_
 #define CHROME_BROWSER_PAGE_LOAD_METRICS_METRICS_WEB_CONTENTS_OBSERVER_H_
 
 #include <map>
 #include <memory>
 #include <vector>
@@ skipping 232 matching lines @@
   const base::TimeTicks navigation_start_;
 
   // Time this page load was committed. If this page load hasn't committed,
   // |commit_time_| will be zero.
   base::TimeTicks commit_time_;
 
   // The URL of this page load. This is the provisional url before commit
   // (before redirects), and the committed url after commit.
   GURL url_;
 
+  // The start URL for this page load (before redirects).
+  GURL start_url_;
+
   std::unique_ptr<FailedProvisionalLoadInfo> failed_provisional_load_info_;
 
   // Will be ABORT_NONE if we have not aborted this load yet. Otherwise will
   // be the first abort action the user performed.
   UserAbortType abort_type_;
 
   // This boolean is only an approximation. As the aborts pipeline is updated,
   // more abort types will have this set to true. Currently, this is only set
   // for navigations aborting navigations.
   bool abort_user_initiated_;
@@ skipping 153 matching lines @@
 
   // Has the MWCO observed at least one navigation?
   bool has_navigated_;
 
   DISALLOW_COPY_AND_ASSIGN(MetricsWebContentsObserver);
 };
 
 }  // namespace page_load_metrics
 
 #endif  // CHROME_BROWSER_PAGE_LOAD_METRICS_METRICS_WEB_CONTENTS_OBSERVER_H_