Replace chromeos::UserManager::Get() with chromeos::GetUserManager().

chrome/browser/chromeos/login/users/user_manager.h

Index: chrome/browser/chromeos/login/users/user_manager.h
diff --git a/chrome/browser/chromeos/login/users/user_manager.h b/chrome/browser/chromeos/login/users/user_manager.h
index dbd8a29b7e11fcde91482df3180bb616751b1cbe..79b57198940080c3cae1c4238b24f9c18cb0cc87 100644
--- a/chrome/browser/chromeos/login/users/user_manager.h
+++ b/chrome/browser/chromeos/login/users/user_manager.h
@@ -381,6 +381,13 @@ class ScopedTestUserManager {
   DISALLOW_COPY_AND_ASSIGN(ScopedTestUserManager);
 };
 
+// Returns the UserManager singleton instance or |NULL| if the singleton has
+// either not been created yet or is already destroyed. This method is not
+// thread-safe and must be called from the main UI thread.
+// Note: Since UserManager class will be moved to compoments/ all clients should
+// use this getter and *not use* GetUserManager().
+UserManager* GetUserManager();
+
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_LOGIN_USERS_USER_MANAGER_H_