Reject the descriptions that attempt to change the order of m= sections

Reject the descriptions that attempt to change the order of m= sections
in current local description.

When setting the descriptions, the order of m= sections would be compared
against existing m= sections and an error would be returned if the order
doesn't match.

Related CL: https://codereview.webrtc.org/3015473002/

BUG=chromium:763842

[Zhi Huang, 2017-09-14 00:33:54]

The CQ bit was checked by zhihuang@webrtc.org to run a CQ dry run

[commit-bot: I haz the power, 2017-09-14 00:34:01]

Dry run: CQ is trying da patch.

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

[Zhi Huang, 2017-09-14 00:35:17]

Description was changed from

==========
Reject the descriptions that attempt to change the order of m= sections
in current local description.

When setting the descriptions, the order of m= sections would be compared
against existing m= sections and an error would be returned if the order
doesn't match.

BUG=chromium:763842
==========

to

==========
Reject the descriptions that attempt to change the order of m= sections
in current local description.

When setting the descriptions, the order of m= sections would be compared
against existing m= sections and an error would be returned if the order
doesn't match.

Related CL: https://codereview.webrtc.org/3015473002/

BUG=chromium:763842
==========

[Zhi Huang, 2017-09-14 00:37:59]

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

[Zhi Huang, 2017-09-14 00:38:00]

PTAL.
This is almost the same as CL https://codereview.webrtc.org/3015473002/

This CL is referring to master/head, while the other one is referring to M62. 

The only different code is the DoSetLocal/RemoteDescription methods.

[Taylor Brandstetter, 2017-09-14 00:42:31]

lgtm with nits (see https://codereview.webrtc.org/3015473002/)

[commit-bot: I haz the power, 2017-09-14 01:02:31]

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

[commit-bot: I haz the power, 2017-09-14 01:02:32]

Dry run: This issue passed the CQ dry run.

[Zhi Huang, 2017-09-14 05:00:48]

Patchset #2 (id:20001) has been deleted

[Zhi Huang, 2017-09-14 05:01:46]

The CQ bit was checked by zhihuang@webrtc.org to run a CQ dry run

[commit-bot: I haz the power, 2017-09-14 05:02:07]

Dry run: 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, 2017-09-14 05:29:49]

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

[commit-bot: I haz the power, 2017-09-14 05:29:50]

Dry run: This issue passed the CQ dry run.

[Zhi Huang, 2017-09-14 05:47:35]

The CQ bit was checked by zhihuang@webrtc.org

[Zhi Huang, 2017-09-14 05:47:36]

The patchset sent to the CQ was uploaded after l-g-t-m from deadbeef@webrtc.org
Link to the patchset: https://codereview.webrtc.org/3012313002/#ps40001 (title:
"Address comments.")

[commit-bot: I haz the power, 2017-09-14 05:47:51]

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, 2017-09-14 05:50:32]

CQ is committing da patch.

Bot data: {"patchset_id": 40001, "attempt_start_ts": 1505368055272490,
"parent_rev": "7a5bcdffaab90a05bc1146b2b1ea71c004e54d71", "commit_rev":
"721d109d12a4a295a20d04e814a5b7b82d08e75d"}

[commit-bot: I haz the power, 2017-09-14 05:50:33]

CQ is committing da patch.

Bot data: {"patchset_id": 40001, "attempt_start_ts": 1505368055272490,
"parent_rev": "7a5bcdffaab90a05bc1146b2b1ea71c004e54d71", "commit_rev":
"721d109d12a4a295a20d04e814a5b7b82d08e75d"}

[commit-bot: I haz the power, 2017-09-14 05:50:35]

CQ is committing da patch.

Bot data: {"patchset_id": 40001, "attempt_start_ts": 1505368055272490,
"parent_rev": "7a5bcdffaab90a05bc1146b2b1ea71c004e54d71", "commit_rev":
"721d109d12a4a295a20d04e814a5b7b82d08e75d"}

[commit-bot: I haz the power, 2017-09-14 05:50:36]

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

[commit-bot: I haz the power, 2017-09-14 05:50:37]

Failed to commit the patch.