Fix crash in permission filter dialog when there are no usages.

    private static final int MAXIMUM_NUM_BARS = 4;

    private @NonNull PermissionUsages mPermissionUsages;

    private @Nullable List<AppPermissionUsage> mAppPermissionUsages;

    private @Nullable List<AppPermissionUsage> mAppPermissionUsages = new ArrayList<>();

    private Collator mCollator;

    private MenuItem mSortByApp;

    private MenuItem mSortByTime;

    private ArrayMap<String, Integer> mGroupAppCounts;

    private ArrayMap<String, Integer> mGroupAppCounts = new ArrayMap<>();

    private boolean mFinishedInitialLoad;

        long startTime = (timeFilterItem == null ? 0 : (curTime - timeFilterItem.getTime()));

        List<Pair<AppPermissionUsage, GroupUsage>> usages = new ArrayList<>();

        mGroupAppCounts = new ArrayMap<>();

        mGroupAppCounts.clear();

        ArrayList<PermissionApp> permApps = new ArrayList<>();

        int numApps = mAppPermissionUsages.size();

        for (int appNum = 0; appNum < numApps; appNum++) {

        int[] groupAccessCounts = new int[groupNames.length];

        groupNames[0] = null;

        groupLabels[0] = context.getString(R.string.permission_usage_any_permission);

        groupAccessCounts[0] = mGroupAppCounts.get(null);

        Integer allAccesses = mGroupAppCounts.get(null);

        if (allAccesses == null) {

            allAccesses = 0;

        }

        groupAccessCounts[0] = allAccesses;

        int selection = 0;

        int numGroups = groups.size();

        for (int i = 0; i < numGroups; i++) {