Move (phase 3) more functions called only in sdp_offer_answer

This is starting to get near the end of code moves.

Bug: webrtc:11995
Change-Id: I2f98e1025970db823c8c51bd9ab9f91f380d78a2
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/186520
Reviewed-by: Björn Terelius <[email protected]>
Commit-Queue: Harald Alvestrand <[email protected]>
Cr-Commit-Position: refs/heads/master@{#32320}

Author: Harald Alvestrand