function filterForKeyword(extensionList, word) {
            var filteredList = [];
            extensionList.forEach(function (id) {
                var entry = self._getEntry(id);
                if (entry && self._entryMatchesQuery(entry, word)) {
                    filteredList.push(id);
                }
            });
            return filteredList;
        }
@private
Searches for the given query in the current extension list and updates the filter set,
dispatching a filter event.
@param {string} query The string to search for.
@param {boolean} force If true, always filter starting with the full set, not the last
    query's filter.