Finish already paused activity if it should be finished after pausing

If the app requests its activity to be finished allow it to be finished
immediately if the activity is already paused.

Bug: 22170595
Change-Id: I1ecc0d5f3b85fd80cbe8cdc1d4e32d5c6a50b20c

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

@@ -2963,6 +2963,7 @@ final class ActivityStack {
         r.state = ActivityState.FINISHING;
 
         if (mode == FINISH_IMMEDIATELY
+                || (mode == FINISH_AFTER_PAUSE && prevState == ActivityState.PAUSED)
                 || prevState == ActivityState.STOPPED
                 || prevState == ActivityState.INITIALIZING) {
             // If this activity is already stopped, we can just finish