Make SetState be called later when screen is unlocking.

The bug's root cause is SetState is called too early when screen is
unlocking and IMF thinks the current UI session is still LOCK screen so
it won't persist the active input method.

BUG=409500
TEST=Verified on Pixel.

Review URL: https://codereview.chromium.org/521463005

Cr-Commit-Position: refs/heads/master@{#292891}

chrome/browser/chromeos/login/lock/screen_locker.cc

@@ -205,17 +205,14 @@ void ScreenLocker::OnAuthSuccess(const UserContext& user_context) {
   const user_manager::User* user =
       user_manager::UserManager::Get()->FindUser(user_context.GetUserID());
   if (user) {
-    if (user->is_active()) {
-      DCHECK(saved_ime_state_);
-      input_method::InputMethodManager::Get()->SetState(saved_ime_state_);
-    } else {
+    if (!user->is_active()) {
+      saved_ime_state_ = NULL;
       user_manager::UserManager::Get()->SwitchActiveUser(
           user_context.GetUserID());
     }
   } else {
     NOTREACHED() << "Logged in user not found.";
   }
-  saved_ime_state_ = NULL;
 
   authentication_capture_.reset(new AuthenticationParametersCapture());
   authentication_capture_->user_context = user_context;
@@ -463,6 +460,10 @@ ScreenLocker::~ScreenLocker() {
   VLOG(1) << "Calling session manager's HandleLockScreenDismissed D-Bus method";
   DBusThreadManager::Get()->GetSessionManagerClient()->
       NotifyLockScreenDismissed();
+
+  if (saved_ime_state_) {
+    input_method::InputMethodManager::Get()->SetState(saved_ime_state_);
+  }
 }
 
 void ScreenLocker::SetAuthenticator(Authenticator* authenticator) {