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This adds UMA metrics for
- Capture time in spent in Blink
- Total capture time
- Usage/Success counters
- Frame count to evaluate total frames captured

Follow-up CLs will be needed for UKMs and disk-usage.

Bug: 1038390
Change-Id: I1b7e0a844da23d23257cb75ad6673ff31a730955
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1986773Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Reviewed-by: Ian Vollick <vollick@chromium.org>
Commit-Queue: Calder Kitagawa <ckitagawa@chromium.org>
Cr-Commit-Position: refs/heads/master@{#734644}