Support entry selection on tracing based timeline flame chart

Details section is not populated yet - will be addressed in the next patch.

BUG=361045
R=loislo@chromium.org

Review URL: https://codereview.chromium.org/297753009

git-svn-id: svn://svn.chromium.org/blink/trunk@174687 bbb929c8-8fbe-4397-9dbb-9b2b20218538