Delete unused class SharedExclusiveLock.

Delete unused class SharedExclusiveLock.

Unused since cl https://codereview.webrtc.org/2828223002/

BUG=webrtc:7501
Review-Url: https://codereview.webrtc.org/2865083002
Cr-Commit-Position: refs/heads/master@{#18050}
Committed: https://chromium.googlesource.com/external/webrtc/+/3f580e24cc315c7dc48f533159b1b49d3e4da820

[nisse-webrtc, 2017-05-08 12:36:16]

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

[nisse-webrtc, 2017-05-08 12:36:36]

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

[commit-bot: I haz the power, 2017-05-08 12:36:44]

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, 2017-05-08 12:56:53]

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

[commit-bot: I haz the power, 2017-05-08 12:56:54]

Dry run: This issue passed the CQ dry run.

[kwiberg-webrtc, 2017-05-08 13:01:42]

kwiberg@webrtc.org changed reviewers:
+ kwiberg@webrtc.org

[kwiberg-webrtc, 2017-05-08 13:01:43]

lgtm!

Provided this doesn't break any WebRTC users, that is. :-)

[nisse-webrtc, 2017-05-08 13:21:50]

The CQ bit was checked by nisse@webrtc.org

[commit-bot: I haz the power, 2017-05-08 13:21:59]

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, 2017-05-08 13:24:30]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1494249710500020, "parent_rev":
"e61103dc6cc279cff81f9955fb7cee3ea3e6599f", "commit_rev":
"3f580e24cc315c7dc48f533159b1b49d3e4da820"}

[commit-bot: I haz the power, 2017-05-08 13:24:34]

Description was changed from

==========
Delete unused class SharedExclusiveLock.

Unused since cl https://codereview.webrtc.org/2828223002/

BUG=webrtc:7501
==========

to

==========
Delete unused class SharedExclusiveLock.

Unused since cl https://codereview.webrtc.org/2828223002/

BUG=webrtc:7501

Review-Url: https://codereview.webrtc.org/2865083002
Cr-Commit-Position: refs/heads/master@{#18050}
Committed:
https://chromium.googlesource.com/external/webrtc/+/3f580e24cc315c7dc48f53315...
==========

[commit-bot: I haz the power, 2017-05-08 13:24:35]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/external/webrtc/+/3f580e24cc315c7dc48f53315...