Add CountQuotaTracker.

        return data.get(tag);

    }

    /**

     * Returns the index for which {@link #getUserIdAtIndex(int)} would return the specified userId,

     * or a negative number if the specified userId is not mapped.

     */

    public int indexOfUserId(int userId) {

        return mData.indexOfKey(userId);

    }

    /**

     * Returns the index for which {@link #getPackageNameAtIndex(int, int)} would return the

     * specified userId, or a negative number if the specified userId and packageName are not mapped

     * together.

     */

    public int indexOfUserIdAndPackage(int userId, @NonNull String packageName) {

        return mData.indexOfKey(userId, packageName);

    }

    /** Returns the userId at the given index. */

    public int getUserIdAtIndex(int index) {

    private int getUserIdAtIndex(int index) {

        return mData.keyAt(index);

    }

    /** Returns the package name at the given index. */

    @NonNull

    public String getPackageNameAtIndex(int userIndex, int packageIndex) {

    private String getPackageNameAtIndex(int userIndex, int packageIndex) {

        return mData.keyAt(userIndex, packageIndex);

    }

    /** Returns the tag at the given index. */

    @NonNull

    public String getTagAtIndex(int userIndex, int packageIndex, int tagIndex) {

    private String getTagAtIndex(int userIndex, int packageIndex, int tagIndex) {

        // This structure never inserts a null ArrayMap, so if the indices are valid, valueAt()

        // won't return null.

        return mData.valueAt(userIndex, packageIndex).keyAt(tagIndex);