Implement title formatting in tracing based timeline

Event titles on timeline flame chart view are now formatted similar to those on regular timeline view.

Also supported event to initiator mapping and event to stack trace mapping.

BUG=361045
R=loislo@chromium.org

Review URL: https://codereview.chromium.org/296893003

git-svn-id: svn://svn.chromium.org/blink/trunk@174454 bbb929c8-8fbe-4397-9dbb-9b2b20218538