Inform WindowManager when Activity is reordered to front.

This event was captured on the ActivityManager side through
TaskRecord::moveActivityToFrontLocked. However, this change was
not conveyed to the WindowManager, leading to potential issues, such
as sending key events to the wrong Activity.

Change-Id: Ia5cf3dc0f2dac8fa10adc775c2ebb08beee0c064
Fixes: 65031003
Test: cts/hostsidetests/services/activityandwindowmanager/util/run-test CtsServicesHostTestCases android.server.cts.ActivityManagerActivityVisibilityTests#testReorderToFrontBackstack
(cherry picked from commit c033f8de620db59ff94ef905a4ab66ac3e212c06)
diff --git a/services/core/java/com/android/server/wm/TaskWindowContainerController.java b/services/core/java/com/android/server/wm/TaskWindowContainerController.java
index 65f8cdf..b3bb0b7 100644
--- a/services/core/java/com/android/server/wm/TaskWindowContainerController.java
+++ b/services/core/java/com/android/server/wm/TaskWindowContainerController.java
@@ -103,6 +103,10 @@
         }
     }
 
+    public void positionChildAtTop(AppWindowContainerController childController) {
+        positionChildAt(childController, POSITION_TOP);
+    }
+
     public void positionChildAt(AppWindowContainerController childController, int position) {
         synchronized(mService.mWindowMap) {
             final AppWindowToken aToken = childController.mContainer;