Finish immediately if the resumed activity is already visible

When in FINISH_AFTER_VISIBLE mode, we need to check visibility of
both the current activity, and the activity to be resumed. If the
resumed activity is already visible, we should finish immediately.
We can't put it into stopping state and wait because there won't be
a window visible callback from the next activity.

bug: 28378359

Change-Id: Ib1fb44acfec33616da76f48102cc00b453e41914
diff --git a/services/core/java/com/android/server/am/ActivityStack.java b/services/core/java/com/android/server/am/ActivityStack.java
index a7c994b..37bd401 100644
--- a/services/core/java/com/android/server/am/ActivityStack.java
+++ b/services/core/java/com/android/server/am/ActivityStack.java
@@ -3457,7 +3457,8 @@
         // First things first: if this activity is currently visible,
         // and the resumed activity is not yet visible, then hold off on
         // finishing until the resumed one becomes visible.
-        if (mode == FINISH_AFTER_VISIBLE && (r.visible || r.nowVisible)) {
+        if (mode == FINISH_AFTER_VISIBLE && (r.visible || r.nowVisible)
+                && !mStackSupervisor.allResumedActivitiesVisible()) {
             if (!mStackSupervisor.mStoppingActivities.contains(r)) {
                 addToStopping(r, false /* immediate */);
             }