Post KeyguardGone request to main Handler so multidisplay keyguards are

dismissed properly.

While keyguard is dismissed, onDisplayChanged is called, which calls
hiding and showing presentations. Dismissing keyguard on these
displays should be done when onDisplayChanged is done processing.

Test: Manual
Bug: 156117648
Change-Id: Ib6d2ce407aef2fee22cfec227d243650b5643c25

packages/CarSystemUI/src/com/android/systemui/car/keyguard/CarKeyguardViewController.java

@@ -188,7 +188,7 @@ public class CarKeyguardViewController extends OverlayViewController implements
         stop();
         getOverlayViewGlobalStateController().setWindowFocusable(/* focusable= */ false);
         mKeyguardStateController.notifyKeyguardDoneFading();
-        mViewMediatorCallback.keyguardGone();
+        mHandler.post(mViewMediatorCallback::keyguardGone);
         notifyKeyguardUpdateMonitor();
     }