Break out code from bloated files in the BWE simulator.

No changes to functionality.

BUG=4173
R=pbos@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/34209004

Cr-Commit-Position: refs/heads/master@{#8374}
git-svn-id: http://webrtc.googlecode.com/svn/trunk@8374 4adac7df-926f-26a2-2b94-8c16560cd09d
15 files changed