This change introduces a new method |GetType()| in
SessionDescriptionInterface which returns an enum for the SDP type
rather than a string. Additionally, new overloads were added for
CreateSessionDescription to take SdpType instead of a type string.
Bug: webrtc:8613
Change-Id: I52b342f12155daf8d623646b0c21b7562f69d101
Reviewed-on: https://webrtc-review.googlesource.com/29380
Reviewed-by: Peter Thatcher <pthatcher@webrtc.org>
Reviewed-by: Zhi Huang <zhihuang@webrtc.org>
Commit-Queue: Steve Anton <steveanton@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21100}
88f2cb9479