UMA track signed in duration at signout

chrome/browser/signin/signin_manager_factory.cc

 // Copyright (c) 2012 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.
 
 #include "chrome/browser/signin/signin_manager_factory.h"
 
 #include "base/prefs/pref_registry_simple.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/signin/chrome_signin_client_factory.h"
@@ skipping 85 matching lines @@
       prefs::kAutologinEnabled,
       true,
       user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
   registry->RegisterBooleanPref(
       prefs::kReverseAutologinEnabled,
       true,
       user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
   registry->RegisterListPref(prefs::kReverseAutologinRejectedEmailList,
                              new base::ListValue,
                              user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
+  registry->RegisterInt64Pref(
+      prefs::kSignedInTime,
+      base::Time().ToInternalValue(),
+      user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
   chrome::RegisterLocalAuthPrefs(registry);
 }
 
 // static
 void SigninManagerFactory::RegisterPrefs(PrefRegistrySimple* registry) {
   registry->RegisterStringPref(prefs::kGoogleServicesUsernamePattern,
                                std::string());
 }
 
 void SigninManagerFactory::AddObserver(Observer* observer) {
@@ skipping 27 matching lines @@
 }
 
 void SigninManagerFactory::BrowserContextShutdown(
     content::BrowserContext* context) {
   SigninManagerBase* manager = static_cast<SigninManagerBase*>(
       GetServiceForBrowserContext(context, false));
   if (manager)
     FOR_EACH_OBSERVER(Observer, observer_list_, SigninManagerShutdown(manager));
   BrowserContextKeyedServiceFactory::BrowserContextShutdown(context);
 }