deadbeef 5ada7acf60 If SRTP sessions exist, don't create new ones when applying answer.
Instead, call the "Update" methods of SrtpSession, which will just call
srtp_update, instead of wiping out the session state completely.

This was causing decryption to stop working when subsequent
offers/answers are applied. We don't know enough about SRTP to
understand the root cause, and I wasn't able to write an integration
test that reproduces the issue... But at least this fixes the bug that
can be reproduced reliably using Hangouts.

BUG=webrtc:8251

Review-Url: https://codereview.webrtc.org/3019443002
Cr-Commit-Position: refs/heads/master@{#19874}
2017-09-16 00:52:36 +00:00
..