Add last video render time to bug reports

The last video render time can be helpful for detecting the point in
time around which a permanent video freeze occurs, allowing one to
pinpoint in system logs other events occurring around that point in
time.

Bug: 293851202
Bug: 295565737
Test: play a video that freezes (see bug) and look at metrics
Change-Id: I4ee46120c825c7e1b7a394e4f20cd5c710a63bc1