GitLab

Adds a deadline overrun step to the RendererSchedulerIdlePeriod trace event
to make it obvious when an idle period lasts longer than its deadline.

Also adds a TRACE_EVENT_ASYNC_STEP_INTO_WITH_TIMESTAMP0 which is required
to add the step at the appropriate time.

BUG=455713

Review URL: https://codereview.chromium.org/908473002

Cr-Commit-Position: refs/heads/master@{#315042}