Fix crash when locking screen while adding a user to an existing session.

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

Index: chrome/browser/chromeos/login/lock/screen_locker_browsertest.cc
diff --git a/chrome/browser/chromeos/login/lock/screen_locker_browsertest.cc b/chrome/browser/chromeos/login/lock/screen_locker_browsertest.cc
index d4c218cc08f11299872384e7306960b22ff6c49e..fb398bbf7d92e7970178c9f76917f5a36033495c 100644
--- a/chrome/browser/chromeos/login/lock/screen_locker_browsertest.cc
+++ b/chrome/browser/chromeos/login/lock/screen_locker_browsertest.cc
@@ -10,6 +10,7 @@
 #include "base/message_loop/message_loop.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/chromeos/login/lock/screen_locker_tester.h"
+#include "chrome/browser/chromeos/login/ui/user_adding_screen.h"
 #include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_window.h"
@@ -173,6 +174,14 @@ IN_PROC_BROWSER_TEST_F(ScreenLockerTest, TestBasic) {
   EXPECT_TRUE(VerifyLockScreenDismissed());
 }
 
+// Makes sure Chrome doesn't crash if we lock the screen during an add-user
+// flow. Regression test for crbug.com/467111.
+IN_PROC_BROWSER_TEST_F(ScreenLockerTest, LockScreenWhileAddingUser) {
+  UserAddingScreen::Get()->Start();
+  content::RunAllPendingInMessageLoop();
+  ScreenLocker::HandleLockScreenRequest();
+}
+
 // Test how locking the screen affects an active fullscreen window.
 IN_PROC_BROWSER_TEST_F(ScreenLockerTest, TestFullscreenExit) {
   // 1) If the active browser window is in fullscreen and the fullscreen window