ash: Merge LoginStatus update code path

ash/wm/lock_state_controller.cc

Index: ash/wm/lock_state_controller.cc
diff --git a/ash/wm/lock_state_controller.cc b/ash/wm/lock_state_controller.cc
index dae6e253db8010f72543267a851f80104f5b0b9b..36f083b129ad0fb6cb6386dc69e291002075e431 100644
--- a/ash/wm/lock_state_controller.cc
+++ b/ash/wm/lock_state_controller.cc
@@ -66,7 +66,6 @@ const int LockStateController::kShutdownRequestDelayMs = 50;
 LockStateController::LockStateController(
     ShutdownController* shutdown_controller)
     : animator_(new SessionStateAnimatorImpl()),
-      login_status_(LoginStatus::NOT_LOGGED_IN),
       system_is_locked_(false),
       shutting_down_(false),
       shutdown_after_lock_(false),
@@ -191,12 +190,6 @@ void LockStateController::OnHostCloseRequested(
   Shell::Get()->shell_delegate()->Exit();
 }
 
-void LockStateController::OnLoginStateChanged(LoginStatus status) {

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

Just to double check... This is safe to remove because OnLockStateChanged() is
always called?

Was this needed in the old code?

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

IIUC, this function is not actually needed. |login_status_| is only set here and
no one uses it. |system_is_locked_| is updated in OnLockStateChanged(). The only
way this can be useful is to set |system_is_locked_| to final state early to
skip the work in OnLockStateChanged(). But it would be disaster when it happens
because it skips post(un)lock animations and leaves the UI in a bad state.

OnLockStateChanged() already ensures the animations run once when
|system_is_locked_| changes. We don't need this function to mess with the state
so skip that.

The old code works because OnLoginStateChanged is only called when a user signs
in and not called when login status changes. So we don't see the two fight with
each other. This fight happens after I chain OnLoginStateChanged from login
status change.

-  if (status != LoginStatus::LOCKED)
-    login_status_ = status;
-  system_is_locked_ = (status == LoginStatus::LOCKED);
-}
-
 void LockStateController::OnAppTerminating() {
   // If we hear that Chrome is exiting but didn't request it ourselves, all we
   // can really hope for is that we'll have time to clear the screen.