DevTools: move timeline presentation model into panel.

This change also moves filters and search onto the panel level as well, introduces timeline mode interface.

Review URL: https://codereview.chromium.org/178093002

git-svn-id: svn://svn.chromium.org/blink/trunk@167749 bbb929c8-8fbe-4397-9dbb-9b2b20218538