Merge "Check if the extcon dir exists when constructing WiredAccessoryExtconObserver"

        /** Returns a new list of all external connections whose name matches {@code regex}. */

        public static List<ExtconInfo> getExtconInfos(@Nullable String regex) {

            if (!extconExists()) {

                return new ArrayList<>(0);  // Always return a new list.

            }

            Pattern p = regex == null ? null : Pattern.compile(regex);

            File file = new File("/sys/class/extcon");

            File[] files = file.listFiles();