Remove DCHECK from PeerConnectionFactory::worker_thread.

Remove DCHECK from PeerConnectionFactory::worker_thread.

PeerConnection::SetBitrate calls PeerConnectionFactory::worker_thread
from multiple threads, so it was triggering the DCHECK. However, the
worker thread never changes after construction, so worker_thread should
be safe to call from multiple threads.

BUG=NONE

Review-Url: https://codereview.webrtc.org/2923953004
Cr-Commit-Position: refs/heads/master@{#18576}
Committed: https://chromium.googlesource.com/external/webrtc/+/179f99730775f1de20f7dd178f7784b0f64df1d9

[Zach Stein, 2017-06-08 21:50:48]

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

[Taylor Brandstetter, 2017-06-09 01:56:48]

We can just remove the DCHECK. It looks like it was added here:
https://webrtc-codereview.appspot.com/35429004

But likely by accident, since the DCHECK was added to a lot of other methods
too. The worker thread never changes after construction so there's no reason I
can think of why it needs to be thread-protected.

[Zach Stein, 2017-06-13 17:50:34]

Description was changed from

==========
Fix failing DCHECK in PeerConnection::SetBitrate.

PeerConnectionFactory::worker_thread() should only be called from
the signaling thread - we were calling it from the signaling thread,
swapping to the worker thread, and then calling it again.

The unittests do not catch this because they only use one thread.

BUG=NONE
==========

to

==========
PeerConnection::SetBitrate calls this from multiple threads, so it was
triggering the DCHECK. The thread never changes after construction, so it should
be safe to call this from multiple threads.

BUG=NONE
==========

[Zach Stein, 2017-06-13 17:52:29]

Description was changed from

==========
PeerConnection::SetBitrate calls this from multiple threads, so it was
triggering the DCHECK. The thread never changes after construction, so it should
be safe to call this from multiple threads.

BUG=NONE
==========

to

==========
PeerConnection::SetBitrate calls PeerConnectionFactory::worker_thread from
multiple threads, so it was triggering the DCHECK. The thread never changes
after construction, so worker_thread should be safe to call from multiple
threads.

BUG=NONE
==========

[Taylor Brandstetter, 2017-06-13 21:41:00]

Description was changed from

==========
PeerConnection::SetBitrate calls PeerConnectionFactory::worker_thread from
multiple threads, so it was triggering the DCHECK. The thread never changes
after construction, so worker_thread should be safe to call from multiple
threads.

BUG=NONE
==========

to

==========
Remove DCHECK from PeerConnectionFactory::worker_thread.

PeerConnection::SetBitrate calls PeerConnectionFactory::worker_thread
from multiple threads, so it was triggering the DCHECK. However, the
worker thread never changes after construction, so worker_thread should
be safe to call from multiple threads.

BUG=NONE
==========

[Taylor Brandstetter, 2017-06-13 21:41:13]

lgtm

[Taylor Brandstetter, 2017-06-13 21:41:28]

The CQ bit was checked by deadbeef@webrtc.org

[commit-bot: I haz the power, 2017-06-13 21:41:41]

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, 2017-06-13 22:01:50]

CQ is committing da patch.

Bot data: {"patchset_id": 20001, "attempt_start_ts": 1497390088515570,
"parent_rev": "da4eba1e0a57e21775e7f9ca00cafdc297d81214", "commit_rev":
"179f99730775f1de20f7dd178f7784b0f64df1d9"}

[commit-bot: I haz the power, 2017-06-13 22:01:54]

Description was changed from

==========
Remove DCHECK from PeerConnectionFactory::worker_thread.

PeerConnection::SetBitrate calls PeerConnectionFactory::worker_thread
from multiple threads, so it was triggering the DCHECK. However, the
worker thread never changes after construction, so worker_thread should
be safe to call from multiple threads.

BUG=NONE
==========

to

==========
Remove DCHECK from PeerConnectionFactory::worker_thread.

PeerConnection::SetBitrate calls PeerConnectionFactory::worker_thread
from multiple threads, so it was triggering the DCHECK. However, the
worker thread never changes after construction, so worker_thread should
be safe to call from multiple threads.

BUG=NONE

Review-Url: https://codereview.webrtc.org/2923953004
Cr-Commit-Position: refs/heads/master@{#18576}
Committed:
https://chromium.googlesource.com/external/webrtc/+/179f99730775f1de20f7dd178...
==========

[commit-bot: I haz the power, 2017-06-13 22:01:55]

Committed patchset #2 (id:20001) as
https://chromium.googlesource.com/external/webrtc/+/179f99730775f1de20f7dd178...