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

ash/login/ui/lock_screen.h

Index: ash/login/ui/lock_screen.h
diff --git a/ash/login/ui/lock_screen.h b/ash/login/ui/lock_screen.h
index fcccca615ae29945b5f6c25c0a8ecbde3d25fc2a..ecad2be6c448050f12ae54dc6f2d6f17a0a347c0 100644
--- a/ash/login/ui/lock_screen.h
+++ b/ash/login/ui/lock_screen.h
@@ -9,12 +9,19 @@
 
 namespace ash {
 
+// TODO(jdufault): There's some internal state here so put ShowLockScreen and
+// DestroyLockScreen inside a (static) class, ie, ash::LockScreen::Show() and
+// ash::LockScreen::Destroy().
+
 // Creates and displays the lock screen. Returns true if the lock screen was
 // displayed.
 //
 // The lock screen communicates with the backend C++ via a mojo API.
 ASH_EXPORT bool ShowLockScreen();
 
+// Destroys the lock screen. There must be an existing lock screen instance.
+ASH_EXPORT void DestroyLockScreen();
+
 }  // namespace ash
 
 #endif  // ASH_LOGIN_UI_LOCK_SCREEN_H_