GitLab

vea_unittest: Calculate per-frame encode latency

Calculates per-frame encode latency, which is basically the time delay from
input of each VideoFrame (VEA::Encode()) to output of the corresponding
BitstreamBuffer (VEA::Client::BitstreamBufferReady()).

It calculates encode latency values at the 50th(median), 75th, and 95th percentiles.

Also fix a wrong comment.

BUG=345181
TEST=Check "Encode latency for the 50%/75%/95%" in output logs.

Review URL: https://codereview.chromium.org/1117853002

Cr-Commit-Position: refs/heads/master@{#329819}