arc: Show migration success notification on the next sign-in after migration.

chrome/browser/chromeos/login/session/user_session_manager.cc

Index: chrome/browser/chromeos/login/session/user_session_manager.cc
diff --git a/chrome/browser/chromeos/login/session/user_session_manager.cc b/chrome/browser/chromeos/login/session/user_session_manager.cc
index 1c9cc4e135106f957beec9bc5c980abb1d2d8b73..9594fa12726e68a2cb2fc282e0a72242271efd2f 100644
--- a/chrome/browser/chromeos/login/session/user_session_manager.cc
+++ b/chrome/browser/chromeos/login/session/user_session_manager.cc
@@ -29,6 +29,7 @@
 #include "chrome/browser/browser_process_platform_part_chromeos.h"
 #include "chrome/browser/browser_shutdown.h"
 #include "chrome/browser/chrome_notification_types.h"
+#include "chrome/browser/chromeos/arc/arc_migration_guide_notification.h"
 #include "chrome/browser/chromeos/arc/arc_service_launcher.h"
 #include "chrome/browser/chromeos/arc/arc_util.h"
 #include "chrome/browser/chromeos/base/locale_util.h"
@@ -1829,6 +1830,10 @@ void UserSessionManager::DoBrowserLaunchInternal(Profile* profile,
   // the message accordingly.
   if (ShouldShowEolNotification(profile))
     CheckEolStatus(profile);
+
+  // Shows and updates the relevant pref for the one-time notification on the

[hidehiko, 2017/04/24 05:59:48]

nit: s/Shows and updates/Show and update/ (please use imperative form, in inline
comments).
Or, maybe "Show the one-time notification and update the relavant pref ..."?

[kinaba, 2017/04/24 06:09:36]

Done.

+  // completion of the file system migration necessary for ARC, when needed.
+  arc::ShowArcMigrationSuccessNotificationIfNeeded(profile);
 }
 
 void UserSessionManager::RespectLocalePreferenceWrapper(