Express audio delay more precisely in frames rather than milliseconds.
This is a first step to reduce drift in audio video synchronization.
With this change, drift in a 2 hour file will be mostly eliminated if
the media sample rate matches that of the hardware (no resampling).
Other sources of drift will be fixed in follow up cls.
BUG=564604,587522,586540
TEST=webm file from reporter in http://crbug.com/564604#c9
Review URL: https://codereview.chromium.org/1687213002
Cr-Commit-Position: refs/heads/master@{#375967}
20 files changed
