Whitelist events visible on tracing based timeline

We use blacklist for records that we want to hide in the old timeline implentation. However, in case of tracing we don't know all event names upfront, so whitelist approach is more appropriate in this case.

BUG=361045

Review URL: https://codereview.chromium.org/385623002

git-svn-id: svn://svn.chromium.org/blink/trunk@177863 bbb929c8-8fbe-4397-9dbb-9b2b20218538