Merge "Dumpstate: Add tombstone filtering" into oc-mr1-dev

 * Returns a vector of dump fds under |dir_path| with a given |file_prefix|.

 * The returned vector is sorted by the mtimes of the dumps. If |limit_by_mtime|

 * is set, the vector only contains files that were written in the last 30 minutes.

 * If |limit_by_count| is set, the vector only contains the ten latest files.

 */

static std::vector<DumpData>* GetDumpFds(const std::string& dir_path,

                                         const std::string& file_prefix,

                                         bool limit_by_mtime) {

                                         bool limit_by_mtime,

                                         bool limit_by_count = true) {

    const time_t thirty_minutes_ago = ds.now_ - 60 * 30;

    std::unique_ptr<std::vector<DumpData>> dump_data(new std::vector<DumpData>());

    std::sort(dump_data->begin(), dump_data->end());

    if (limit_by_count && dump_data->size() > 10) {

        dump_data->erase(dump_data->begin() + 10, dump_data->end());

    }

    return dump_data.release();

}