GitLab

Histograms in json format:
* capture time
* encode time
* packet latency
* frame latency
* playout delay

- Duration in ms
- first event unix time
- last event unix time

Also improved ReceiverTimeOffsetEstimatorImpl to re-estimate every 30 seconds to account for unknown amount of clock drift between sender and receiver.
BUG=403921

Review URL: https://codereview.chromium.org/482383005

Cr-Commit-Position: refs/heads/master@{#291873}