ash: Merge LoginStatus update code path

ash/common/session/session_state_observer.h

Index: ash/common/session/session_state_observer.h
diff --git a/ash/common/session/session_state_observer.h b/ash/common/session/session_state_observer.h
index 83aefd7e74bc175d75949c962079119fcf8bb222..a6d3ddd282e812419fa5ec1d665a8e9d63eb47e5 100644
--- a/ash/common/session/session_state_observer.h
+++ b/ash/common/session/session_state_observer.h
@@ -13,6 +13,8 @@ class AccountId;
 
 namespace ash {
 
+enum class LoginStatus;
+
 class ASH_EXPORT SessionStateObserver {
  public:
   // Called when active user has changed.
@@ -27,6 +29,9 @@ class ASH_EXPORT SessionStateObserver {
   // Called when session state is changed.
   virtual void SessionStateChanged(session_manager::SessionState state) {}
 
+  // Called when login status is changed.

[James Cook, 2017/04/05 00:16:24]

mention that |login_status| is the new status

[xiyuan, 2017/04/05 22:29:07]

Done.

+  virtual void LoginStatusChanged(LoginStatus login_status) {}
+
  protected:
   virtual ~SessionStateObserver() {}
 };