Fix SDP stream ID mismatch issue when a track's stream changes.

Fix SDP stream ID mismatch issue when a track's stream changes.

The example that brought up this issue was:
1. Do offer/answer exchange.
2. Later, remove the audio/video stream.
3. Add back a new stream, that contains only the audio track.
4. Do new offer/answer.

The new offer didn't have the new stream ID, but code elsewhere was
expecting one. As a result, the send stream is never hooked up to the
audio track, and audio packets aren't sent.

BUG=chromium:611708
Review-Url: https://codereview.webrtc.org/2810733003
Cr-Commit-Position: refs/heads/master@{#17709}
Committed: https://chromium.googlesource.com/external/webrtc/+/2f425aa6b52b02f36951830d79c2eadd5477f6af

[Taylor Brandstetter, 2017-04-10 17:48:44]

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

[Taylor Brandstetter, 2017-04-10 17:48:45]

PTAL

[pthatcher1, 2017-04-13 21:31:22]

https://codereview.webrtc.org/2810733003/diff/1/webrtc/pc/mediasession.cc
File webrtc/pc/mediasession.cc (right):

https://codereview.webrtc.org/2810733003/diff/1/webrtc/pc/mediasession.cc#new...
webrtc/pc/mediasession.cc:451: StreamParams* param =
GetStreamByIds(*current_streams, "", stream_it->id);
Instead of making this non-const and adding all this functions to return a
non-const, why not just make a new non-const StreamParams from the const one and
then add that to the content_description down below?

https://codereview.webrtc.org/2810733003/diff/1/webrtc/pc/mediasession.cc#new...
webrtc/pc/mediasession.cc:503: // cname if necessary.
Can you explain why this is necessary in the comment?

Also, why does the cname come from options instead of stream_it->cname?

[Taylor Brandstetter, 2017-04-14 15:52:08]

https://codereview.webrtc.org/2810733003/diff/1/webrtc/pc/mediasession.cc
File webrtc/pc/mediasession.cc (right):

https://codereview.webrtc.org/2810733003/diff/1/webrtc/pc/mediasession.cc#new...
webrtc/pc/mediasession.cc:451: StreamParams* param =
GetStreamByIds(*current_streams, "", stream_it->id);
On 2017/04/13 21:31:21, pthatcher1 wrote:
> Instead of making this non-const and adding all this functions to return a
> non-const, why not just make a new non-const StreamParams from the const one
and
> then add that to the content_description down below?  

Just because this way is more convenient/efficient, and I don't see any reason
to not return non-const pointers.

https://codereview.webrtc.org/2810733003/diff/1/webrtc/pc/mediasession.cc#new...
webrtc/pc/mediasession.cc:503: // cname if necessary.
On 2017/04/13 21:31:22, pthatcher1 wrote:
> Can you explain why this is necessary in the comment?
> 
> Also, why does the cname come from options instead of stream_it->cname?

Done. And there is no stream_it->cname.

[pthatcher1, 2017-04-14 17:00:45]

lgtm

[Taylor Brandstetter, 2017-04-14 17:16:57]

The CQ bit was checked by deadbeef@webrtc.org

[Taylor Brandstetter, 2017-04-14 17:16:58]

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/2810733003/#ps40001 (title:
"Change name of test.")

[commit-bot: I haz the power, 2017-04-14 17:17:04]

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, 2017-04-14 17:41:33]

CQ is committing da patch.

Bot data: {"patchset_id": 40001, "attempt_start_ts": 1492190217848260,
"parent_rev": "0c99514240f39ff72a697af22c186fc4027f077d", "commit_rev":
"2f425aa6b52b02f36951830d79c2eadd5477f6af"}

[commit-bot: I haz the power, 2017-04-14 17:41:37]

Description was changed from

==========
Fix SDP stream ID mismatch issue when a track's stream changes.

The example that brought up this issue was:
1. Do offer/answer exchange.
2. Later, remove the audio/video stream.
3. Add back a new stream, that contains only the audio track.
4. Do new offer/answer.

The new offer didn't have the new stream ID, but code elsewhere was
expecting one. As a result, the send stream is never hooked up to the
audio track, and audio packets aren't sent.

BUG=chromium:611708
==========

to

==========
Fix SDP stream ID mismatch issue when a track's stream changes.

The example that brought up this issue was:
1. Do offer/answer exchange.
2. Later, remove the audio/video stream.
3. Add back a new stream, that contains only the audio track.
4. Do new offer/answer.

The new offer didn't have the new stream ID, but code elsewhere was
expecting one. As a result, the send stream is never hooked up to the
audio track, and audio packets aren't sent.

BUG=chromium:611708

Review-Url: https://codereview.webrtc.org/2810733003
Cr-Commit-Position: refs/heads/master@{#17709}
Committed:
https://chromium.googlesource.com/external/webrtc/+/2f425aa6b52b02f36951830d7...
==========

[commit-bot: I haz the power, 2017-04-14 17:41:38]

Committed patchset #3 (id:40001) as
https://chromium.googlesource.com/external/webrtc/+/2f425aa6b52b02f36951830d7...