cros: Make sure views-based lock screen is destroyed after it is dismissed.

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

Index: chrome/browser/chromeos/login/lock/webui_screen_locker.cc
diff --git a/chrome/browser/chromeos/login/lock/webui_screen_locker.cc b/chrome/browser/chromeos/login/lock/webui_screen_locker.cc
index d7f5cb14a2940383dd46409b19566c01a7016cab..08d3b82528cc4411ab8e21e4615f8df67d915265 100644
--- a/chrome/browser/chromeos/login/lock/webui_screen_locker.cc
+++ b/chrome/browser/chromeos/login/lock/webui_screen_locker.cc
@@ -317,7 +317,8 @@ bool WebUIScreenLocker::IsSigninInProgress() const {
 
 void WebUIScreenLocker::Login(const UserContext& user_context,
                               const SigninSpecifics& specifics) {
-  chromeos::ScreenLocker::default_screen_locker()->Authenticate(user_context);
+  chromeos::ScreenLocker::default_screen_locker()->Authenticate(
+      user_context, base::BindOnce([](bool auth_success) {}));

[xiyuan, 2017/06/06 22:37:52]

nit: Use ScreenLocker::AuthenticateCallback() to create a null callback since we
don't care.

[jdufault, 2017/06/07 18:58:35]

Done.

 }
 
 void WebUIScreenLocker::MigrateUserData(const std::string& old_password) {