Support getting external HMAC auth context with libsrtp 2.1.0.

Support getting external HMAC auth context with libsrtp 2.1.0.

This is in preparation of upgrading to libsrtp 2.1.0.

BUG=webrtc:7856
Review-Url: https://codereview.webrtc.org/2958123002
Cr-Commit-Position: refs/heads/master@{#18805}
Committed: https://chromium.googlesource.com/external/webrtc/+/03fa534fccec0004b27a0db9541def9a324ef675

[joachim, 2017-06-27 21:15:15]

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

[joachim, 2017-06-27 21:15:16]

https://codereview.webrtc.org/2958123002/diff/1/webrtc/pc/srtpfilter.cc
File webrtc/pc/srtpfilter.cc (right):

https://codereview.webrtc.org/2958123002/diff/1/webrtc/pc/srtpfilter.cc#newco...
webrtc/pc/srtpfilter.cc:568: #if defined(SRTP_MAX_MKI_LEN)
The #define has been introduced in libsrtp 2.1.0

[Taylor Brandstetter, 2017-06-28 10:18:33]

lgtm

[Taylor Brandstetter, 2017-06-28 10:18:36]

The CQ bit was checked by deadbeef@webrtc.org

[commit-bot: I haz the power, 2017-06-28 10:18:47]

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, 2017-06-28 10:35:58]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1498645116588580, "parent_rev":
"8cb4397fa0a2515b3bad9c9e2213372ae467998a", "commit_rev":
"03fa534fccec0004b27a0db9541def9a324ef675"}

[commit-bot: I haz the power, 2017-06-28 10:36:02]

Description was changed from

==========
Support getting external HMAC auth context with libsrtp 2.1.0.

This is in preparation of upgrading to libsrtp 2.1.0.

BUG=webrtc:7856
==========

to

==========
Support getting external HMAC auth context with libsrtp 2.1.0.

This is in preparation of upgrading to libsrtp 2.1.0.

BUG=webrtc:7856

Review-Url: https://codereview.webrtc.org/2958123002
Cr-Commit-Position: refs/heads/master@{#18805}
Committed:
https://chromium.googlesource.com/external/webrtc/+/03fa534fccec0004b27a0db95...
==========

[commit-bot: I haz the power, 2017-06-28 10:36:03]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/external/webrtc/+/03fa534fccec0004b27a0db95...