Remove vestigial directorKey code.

        // selection must be tracked separately.

        private final Set<String> mSelection;

        private final Set<String> mProvisionalSelection;

        private String mDirectoryKey;

        public Selection() {

            mSelection = new HashSet<String>();

        /**

         * Used by CREATOR.

         */

        private Selection(String directoryKey, Set<String> selection) {

            mDirectoryKey = directoryKey;

        private Selection(Set<String> selection) {

            mSelection = selection;

            mProvisionalSelection = new HashSet<String>();

        }

                  mProvisionalSelection.equals(((Selection) that).mProvisionalSelection);

        }

        /**

         * Sets the state key for this selection, which allows us to match selections

         * to particular states (of DirectoryFragment). Basically this lets us avoid

         * loading a persisted selection in the wrong directory.

         */

        public void setDirectoryKey(String key) {

            mDirectoryKey = key;

        }

        /**

         * Sets the state key for this selection, which allows us to match selections

         * to particular states (of DirectoryFragment). Basically this lets us avoid

         * loading a persisted selection in the wrong directory.

         */

        public boolean hasDirectoryKey(String key) {

            return key.equals(mDirectoryKey);

        }

        @Override

        public int describeContents() {

            return 0;

        @Override

        public void writeToParcel(Parcel dest, int flags) {

            dest.writeString(mDirectoryKey);

            dest.writeStringList(new ArrayList<>(mSelection));

            // We don't include provisional selection since it is

            // typically coupled to some other runtime state (like a band).

            @Override

            public Selection createFromParcel(Parcel in, ClassLoader loader) {

                String directoryKey = in.readString();

                ArrayList<String> selected = new ArrayList<>();

                in.readStringList(selected);

                return new Selection(directoryKey, new HashSet<String>(selected));

                return new Selection(new HashSet<String>(selected));

            }

            @Override