Add video send SSRC to RtpParameters, and don't allow changing SSRC.

Add video send SSRC to RtpParameters, and don't allow changing SSRC.

With this, RtpSender and RtpReceiver will always return an SSRC if one
is available. Also, attempts to change the SSRC with SetParameters will
fail, rather than silently doing nothing.

BUG=webrtc:6888
Review-Url: https://codereview.webrtc.org/2567333004
Cr-Commit-Position: refs/heads/master@{#15939}
Committed: https://chromium.googlesource.com/external/webrtc/+/fb2aceded614a34311f15396a27fdfacc36bf384

[Taylor Brandstetter, 2016-12-14 03:54:37]

deadbeef@webrtc.org changed reviewers:
+ pthatcher@webrtc.org

[pthatcher1, 2016-12-14 19:01:38]

lgtm, with some minor recommendations

https://codereview.webrtc.org/2567333004/diff/20001/webrtc/media/engine/webrt...
File webrtc/media/engine/webrtcvideoengine2.cc (right):

https://codereview.webrtc.org/2567333004/diff/20001/webrtc/media/engine/webrt...
webrtc/media/engine/webrtcvideoengine2.cc:1564:
RTC_CHECK(!parameters_.config.rtp.ssrcs.empty());
This might happen down the road when we support MID only and no signaled SSRCs. 
It might be easier to just change the code now to be:

if (!parameters_.config.rtp.ssrcs.empty()) {
  rtp_parameters_.encodings[0].ssrc =
rtc::Optional<uint32_t>(parameters_.config.rtp.ssrcs[0]);
}

https://codereview.webrtc.org/2567333004/diff/20001/webrtc/media/engine/webrt...
webrtc/media/engine/webrtcvideoengine2.cc:1877: LOG(LS_ERROR) << "Attempted to
set RtpParameters with modified SSRC";
You might as well use a for-loop here that will be robust for when we add more
than one encoding.

[Taylor Brandstetter, 2016-12-15 00:04:27]

https://codereview.webrtc.org/2567333004/diff/20001/webrtc/media/engine/webrt...
File webrtc/media/engine/webrtcvideoengine2.cc (right):

https://codereview.webrtc.org/2567333004/diff/20001/webrtc/media/engine/webrt...
webrtc/media/engine/webrtcvideoengine2.cc:1564:
RTC_CHECK(!parameters_.config.rtp.ssrcs.empty());
On 2016/12/14 19:01:38, pthatcher1 wrote:
> This might happen down the road when we support MID only and no signaled
SSRCs. 
> It might be easier to just change the code now to be:
> 
> if (!parameters_.config.rtp.ssrcs.empty()) {
>   rtp_parameters_.encodings[0].ssrc =
> rtc::Optional<uint32_t>(parameters_.config.rtp.ssrcs[0]);
> }

When that change occurs, we can update this RTC_CHECK and add a unit test for
the newly-supported behavior, but for now I think the check serves its purpose.

[Taylor Brandstetter, 2016-12-15 00:04:31]

The CQ bit was checked by deadbeef@webrtc.org

[commit-bot: I haz the power, 2016-12-15 00:04:34]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.webrtc.org/...

[commit-bot: I haz the power, 2016-12-15 00:20:04]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-12-15 00:20:05]

Try jobs failed on following builders:
  android_rel on master.tryserver.webrtc (JOB_FAILED,
http://build.chromium.org/p/tryserver.webrtc/builders/android_rel/builds/19385)

[Taylor Brandstetter, 2016-12-16 04:22:24]

Actually I think I'll do the Android/iOS changes in a separate CL.

[Taylor Brandstetter, 2017-01-07 06:15:46]

The CQ bit was checked by deadbeef@webrtc.org

[Taylor Brandstetter, 2017-01-07 06:15:47]

The patchset sent to the CQ was uploaded after l-g-t-m from pthatcher@webrtc.org
Link to the patchset: https://codereview.webrtc.org/2567333004/#ps100001 (title:
"Back out Obj-C and Java changes (were landed separately)")

[commit-bot: I haz the power, 2017-01-07 06:15:49]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.webrtc.org/...

[commit-bot: I haz the power, 2017-01-07 07:05:38]

CQ is committing da patch.

Bot data: {"patchset_id": 100001, "attempt_start_ts": 1483769746854200,
"parent_rev": "0aeaa91219a9181b485ce5cdb7ed2a22ef8cd969", "commit_rev":
"fb2aceded614a34311f15396a27fdfacc36bf384"}

[commit-bot: I haz the power, 2017-01-07 07:05:40]

Description was changed from

==========
Add video send SSRC to RtpParameters, and don't allow changing SSRC.

With this, RtpSender and RtpReceiver will always return an SSRC if one
is available. Also, attempts to change the SSRC with SetParameters will
fail, rather than silently doing nothing.

BUG=webrtc:6888
==========

to

==========
Add video send SSRC to RtpParameters, and don't allow changing SSRC.

With this, RtpSender and RtpReceiver will always return an SSRC if one
is available. Also, attempts to change the SSRC with SetParameters will
fail, rather than silently doing nothing.

BUG=webrtc:6888

Review-Url: https://codereview.webrtc.org/2567333004
Cr-Commit-Position: refs/heads/master@{#15939}
Committed:
https://chromium.googlesource.com/external/webrtc/+/fb2aceded614a34311f15396a...
==========

[commit-bot: I haz the power, 2017-01-07 07:05:41]

Committed patchset #6 (id:100001) as
https://chromium.googlesource.com/external/webrtc/+/fb2aceded614a34311f15396a...