Telemetry: Limit timeline to action time ranges.

We don't want to measure other traces that will just add
noise. This filters all traces using the action ranges.

We also reset the metric every iteration to ensure no
stale ranges are left in the metric.

BUG=334520
NOTRY=true

No-try since I just tried it and only changed one line (and tested that locally).

Review URL: https://codereview.chromium.org/141573002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@245733 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 245733