Clean the SingletonLock only if there is no previous Chromium process running.

chrome/browser/chrome_browser_main.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_CHROME_BROWSER_MAIN_H_
 #define CHROME_BROWSER_CHROME_BROWSER_MAIN_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "base/gtest_prod_util.h"
 #include "base/metrics/field_trial.h"
 #include "base/tracked_objects.h"
 #include "chrome/browser/first_run/first_run.h"
+#include "chrome/browser/process_singleton.h"
 #include "content/browser/browser_main.h"
 
 class BrowserProcessImpl;
 class FieldTrialSynchronizer;
 class HistogramSynchronizer;
 class MetricsService;
 class PrefService;
-class ProcessSingleton;
 class Profile;
 class ShutdownWatcherHelper;
 class TranslateManager;
 
 namespace chrome_browser {
 // For use by ShowMissingLocaleMessageBox.
 extern const char kMissingLocaleDataTitle[];
 extern const char kMissingLocaleDataMessage[];
 }
 
@@ skipping 74 matching lines @@
   // Members initialized after / released before main_message_loop_ ------------
 
   scoped_ptr<BrowserProcessImpl> browser_process_;
   scoped_refptr<HistogramSynchronizer> histogram_synchronizer_;
   scoped_ptr<ProcessSingleton> process_singleton_;
   scoped_ptr<FirstRun::MasterPrefs> master_prefs_;
   bool record_search_engine_;
   TranslateManager* translate_manager_;
   Profile* profile_;
   bool run_message_loop_;
+  ProcessSingleton::NotifyResult notify_result_;
 
   // Initialized in SetupMetricsAndFieldTrials.
   scoped_refptr<FieldTrialSynchronizer> field_trial_synchronizer_;
 
   FRIEND_TEST(BrowserMainTest, WarmConnectionFieldTrial_WarmestSocket);
   FRIEND_TEST(BrowserMainTest, WarmConnectionFieldTrial_Random);
   FRIEND_TEST(BrowserMainTest, WarmConnectionFieldTrial_Invalid);
   DISALLOW_COPY_AND_ASSIGN(ChromeBrowserMainParts);
 };
 
@@ skipping 13 matching lines @@
 // Records the time from our process' startup to the present time in
 // the UMA histogram |metric_name|.
 void RecordBrowserStartupTime();
 
 // Records a time value to an UMA histogram in the context of the
 // PreReadExperiment field-trial. This also reports to the appropriate
 // sub-histogram (_PreRead(Enabled|Disabled)).
 void RecordPreReadExperimentTime(const char* name, base::TimeDelta time);
 
 #endif  // CHROME_BROWSER_CHROME_BROWSER_MAIN_H_