Delete ACMGenericCodec::Encode and use AudioEncoder::Encode directly

Move timestamp conversion out of ACMGenericCodec. Also remove lock
from ACMGenericCodec since the instance is always protected by
acm_crit_sect_ in AudioCodingModuleImpl.

Restructuring the code in AudioCodingModuleImpl::Encode to streamline
the use of locks.

R=minyue@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/46479004

Cr-Commit-Position: refs/heads/master@{#8773}
git-svn-id: http://webrtc.googlecode.com/svn/trunk@8773 4adac7df-926f-26a2-2b94-8c16560cd09d
6 files changed