[Cleanup] Migrate ChromeBrowserMainExtraPartsMetrics to use the Task Scheduler.
This also changes the timing with which startup metrics are recorded: Previously they were recorded ~45 seconds after startup; now they're recorded whenever the TaskScheduler schedules them to be. This is not expected to change the values recorded to these metrics.
BUG=667892, 741816
TEST=none
R=asvitkine@chromium.org
Review-Url: https://codereview.chromium.org/2955063005
Cr-Commit-Position: refs/heads/master@{#486114}
1 file changed