Remove JsepSessionDescription's string Initialize method

Most clients already use webrtc::CreateSessionDescription which
does the same thing and has the benefit of initializing in one
step instead of two and freeing the newly-created session
description if there was a parse error.

Bug: None
Change-Id: Ibeafdf7a6dd73eaea696700bc5eb420838371b75
Reviewed-on: https://chromium-review.googlesource.com/662402
Reviewed-by: Taylor Brandstetter <deadbeef@webrtc.org>
Commit-Queue: Steve Anton <steveanton@webrtc.org>
Cr-Original-Commit-Position: refs/heads/master@{#19808}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 6d64e9a4e0d4dcbf741584e0fc77bf8bedc50fc4
4 files changed