Make BootTimesLoader marker usage thread safe

chrome/browser/chromeos/boot_times_loader.h

 // Copyright (c) 2011 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_CHROMEOS_BOOT_TIMES_LOADER_H_
 #define CHROME_BROWSER_CHROMEOS_BOOT_TIMES_LOADER_H_
 #pragma once
 
 #include <set>
 #include <string>
@@ skipping 122 matching lines @@
   class TimeMarker {
    public:
     TimeMarker(const std::string& name, bool send_to_uma)
         : name_(name),
           time_(base::Time::NowFromSystemTime()),
           send_to_uma_(send_to_uma) {}
     std::string name() const { return name_; }
     base::Time time() const { return time_; }
     bool send_to_uma() const { return send_to_uma_; }
 
+    // comparitor for sorting
+    bool operator<(const TimeMarker& other) const {
+      return time_ < other.time_;
+    }
+
    private:
     friend class std::vector<TimeMarker>;
     std::string name_;
     base::Time time_;
     bool send_to_uma_;
   };
 
   struct Stats {
    public:
     std::string uptime;
     std::string disk;
   };
 
   static void RecordStats(
       const std::string& name, const Stats& stats);
   static Stats GetCurrentStats();
   static void WriteTimes(const std::string base_name,
                          const std::string uma_name,
                          const std::string uma_prefix,
-                         const std::vector<TimeMarker> login_times);
+                         std::vector<TimeMarker> login_times);
+  static void AddMarker(
+      std::vector<TimeMarker>* vector, const TimeMarker& marker);
+  static void AddMarkerImpl(std::vector<TimeMarker>* vector, TimeMarker marker);
+
   void LoginDone();
 
   // Used to hold the stats at main().
   Stats chrome_main_stats_;
   scoped_refptr<Backend> backend_;
 
   // Used to track notifications for login.
   content::NotificationRegistrar registrar_;
   base::AtomicSequenceNumber num_tabs_;
   bool have_registered_;
 
   std::vector<TimeMarker> login_time_markers_;
   std::vector<TimeMarker> logout_time_markers_;
   std::set<RenderWidgetHost*> render_widget_hosts_loading_;
 
   DISALLOW_COPY_AND_ASSIGN(BootTimesLoader);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_BOOT_TIMES_LOADER_H_