GitLab

Since we have been unable to join on the VideoDecoderStats table due to
processing times and lack of cross correlation per resolution, metrics
leadership has asked we add this field directly to watch time
calculations.

This adds a new callback to the WatchTimeReporter for pulling the
PipelineStatistics object (just like VideoDecodeStatsReporter does)
and uses that to collect an initial and then subsequent relative values
as watch time reporting ticks along.

BUG=1002567
TEST=updated unittests
R=chcunningham

Change-Id: I3cf3a3bf779021e9677d8b511a8066efdeeb492b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1869341
Commit-Queue: Dale Curtis <dalecurtis@chromium.org>
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Reviewed-by: Chrome Cunningham <chcunningham@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#709240}