Merge "Defer stop for all activities becoming invisible" into pi-dev

    void addToStopping(ActivityRecord r, boolean scheduleIdle, boolean idleDelayed) {

        if (!mStackSupervisor.mStoppingActivities.contains(r)) {

            mStackSupervisor.mStoppingActivities.add(r);

            // Some activity is waiting for another activity to become visible before it's being

            // stopped, which means that we also want to wait with stopping this one to avoid

            // flickers.

            if (!mStackSupervisor.mActivitiesWaitingForVisibleActivity.isEmpty()

                    && !mStackSupervisor.mActivitiesWaitingForVisibleActivity.contains(r)) {

                if (DEBUG_SWITCH) Slog.i(TAG_SWITCH, "adding to waiting visible activity=" + r

                        + " existing=" + mStackSupervisor.mActivitiesWaitingForVisibleActivity);

                mStackSupervisor.mActivitiesWaitingForVisibleActivity.add(r);

            }

        }

        // If we already have a few activities waiting to stop, then give up

                        stops = new ArrayList<>();

                    }

                    stops.add(s);

                    // Make sure to remove it in all cases in case we entered this block with

                    // shouldSleepOrShutDown

                    mActivitiesWaitingForVisibleActivity.remove(s);

                    mStoppingActivities.remove(activityNdx);

                }

            }