Adds a new UMA histogram to measure the NTP load time since navigation

chrome/browser/ui/webui/ntp/ntp_user_data_logger.h

 // Copyright 2013 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_UI_WEBUI_NTP_NTP_USER_DATA_LOGGER_H_
 #define CHROME_BROWSER_UI_WEBUI_NTP_NTP_USER_DATA_LOGGER_H_
 
 #include <string>
 
 #include "base/strings/string16.h"
@@ skipping 80 matching lines @@
   // for a failed thumbnail.
   size_t number_of_gray_tile_fallbacks_;
 
   // The number of times an external tile, for which the visual appearance is
   // handled by the page itself, was the fallback for a failed thumbnail.
   size_t number_of_external_tile_fallbacks_;
 
   // Total number of mouseovers for this NTP session.
   size_t number_of_mouseovers_;
 
+  // Time from navigation start it took to load the NTP in milliseconds.
+  base::TimeDelta load_time_;
+
+  // Whether we have already emitted NTP stats for this web contents.
+  bool has_emitted_;
+
   // The URL of this New Tab Page - varies based on NTP version.
   GURL ntp_url_;
 
   DISALLOW_COPY_AND_ASSIGN(NTPUserDataLogger);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_NTP_NTP_USER_DATA_LOGGER_H_