Pass VideoDecoderParams to VideoDecoderFactory and add SSRC to RtpEncodingParameters.

VideoDecoderParams contains the id of the receive video
stream. Motivation behind this change is to enable down
stream apps easier map raw non-decoded data to incoming
streams.

BUG=b/28636393

Review-Url: https://codereview.webrtc.org/2052233002
Cr-Original-Commit-Position: refs/heads/master@{#13250}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 1fd959593677a3b2978c488bd796e966f8025b42
6 files changed