Delay audio rendering until the clock reaches the first timestamp.

Since AudioClock no longer looks at timestamps, indeed they've been
completely removed from AudioRendererAlgorithm, ARI::Render() has no
way to correct for media where the video starts before the audio.

We don't want to add timestamp information back everywhere, so this
change just tracks the first decoded timestamp received and uses
that to delay rendering (by writing silence) until the appropriate
time is reached.

Since this may result in partial fills, AudioRendererAlgorithm has
been extended to include an offset into the buffer for writing.

BUG=435908
TEST=new unittest, sample media works.

Review URL: https://codereview.chromium.org/757733003

Cr-Commit-Position: refs/heads/master@{#305727}

0 files changed, 0 insertions, 0 deletions