Update visibility in moveTaskToBack if nothing is resumed

If it's possible that nothing will be resumed by moveTaskToBack (ie.
moving a freeform window to back in a multi-resume environment), then
we need to ensure that visibility is updated after re-ordering since
there will be no lifecycle changes to do it.

Bug: 134182971
Test: Open an app in freeform and move it to back. Observe it
      going invisible with a transition.

Change-Id: Iee7457ba7b8a7dc8385bed3a9434ab7c2490f14a

services/core/java/com/android/server/wm/ActivityStack.java

@@ -4979,6 +4979,17 @@ class ActivityStack extends ConfigurationContainer {
             return true;
         }
 
+        ActivityRecord topActivity = getDisplay().topRunningActivity();
+        ActivityStack topStack = topActivity.getActivityStack();
+        if (topStack != null && topStack != this && topActivity.isState(RESUMED)) {
+            // The new top activity is already resumed, so there's a good chance that nothing will
+            // get resumed below. So, update visibility now in case the transition is closed
+            // prematurely.
+            mRootActivityContainer.ensureVisibilityAndConfig(null /* starting */,
+                    getDisplay().mDisplayId, false /* markFrozenIfConfigChanged */,
+                    false /* deferResume */);
+        }
+
         mRootActivityContainer.resumeFocusedStacksTopActivities();
         return true;
     }