Enhance bootstat_summary to accept a list of events. If provided with arguments, the script will summarize only the named events. If no arguments are provided, the script summarizes all available events, just as before. BUG=None TEST=run the command with and without arguments Change-Id: I21fdcced548d5a1d63c62b8e40f3817342319c46 Reviewed-on: https://gerrit.chromium.org/gerrit/48821 Reviewed-by: Daniel Erat <[email protected]> Commit-Queue: Richard Barnette <[email protected]> Tested-by: Richard Barnette <[email protected]> Reviewed-by: Sonny Rao <[email protected]>