Merge "Allow back predict when no more activity below adjacnet task fragment." into main

            final TaskFragment prevTFAdjacent = prevTF.getAdjacentTaskFragment();

            if (prevTFAdjacent != null) {

                if (prevTFAdjacent == currTF) {

                    // Cannot predict what will happen when app receive back key, skip animation.

                    outPrevActivities.clear();

                    return false;

                    // No more activity in previous task fragment, so it can predict if previous

                    // task exists. Otherwise, unable to predict what will happen when app receive

                    // back key, skip animation.

                    return prevTF.getActivity((below) -> !below.finishing, prevActivity,

                            false /*includeBoundary*/, true /*traverseTopToBottom*/) == null;

                } else {

                    final ActivityRecord prevActivityAdjacent =

                            prevTFAdjacent.getTopNonFinishingActivity();