Revert of Relanding: Fixing crash that can occur if signal is modified while firing.

Revert of Relanding: Fixing crash that can occur if signal is modified while firing. (patchset #4 id:60001 of https://codereview.webrtc.org/2846593005/ )

Reason for revert:
Breaks XmppConnectionTest in Chrome.

https://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_tsan_rel_ng/builds/65096

Original issue's description:
> Relanding: Fixing crash that can occur if signal is modified while firing.
> 
> The crash occurs if a slot causes the very next slot in iteration order
> to be disconnected.
> 
> Relanding after fixing a race condition that this CL revealed. Previously
> the race resulted in an invalidated iterator, but now it will result in the
> iterator being modified, so TSan catches it.
> 
> BUG=webrtc:7527
> 
> Review-Url: https://codereview.webrtc.org/2846593005
> Cr-Original-Commit-Position: refs/heads/master@{#17943}
> Committed: https://chromium.googlesource.com/external/webrtc/+/961c2adf1ea25bcc40ad64cae1ac2ea258e26de2
> Review-Url: https://codereview.webrtc.org/2846593005
> Cr-Commit-Position: refs/heads/master@{#17965}
> Committed: https://chromium.googlesource.com/external/webrtc/+/fc1af0155718d029a97fddfd64422e9e6e509809

TBR=pthatcher@webrtc.org,deadbeef@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=webrtc:7527
Review-Url: https://codereview.webrtc.org/2859443002
Cr-Commit-Position: refs/heads/master@{#17975}
Committed: https://chromium.googlesource.com/external/webrtc/+/de1590919f4aa01c7b70474c9cde733faef87596

[perkj_webrtc, 2017-05-02 13:14:44]

The CQ bit was checked by perkj@webrtc.org

[perkj_webrtc, 2017-05-02 13:14:44]

Created Revert of Relanding: Fixing crash that can occur if signal is modified
while firing.

[commit-bot: I haz the power, 2017-05-02 13:14:54]

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, 2017-05-02 13:15:00]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1493730884347150, "parent_rev":
"d71ebd70f6c40a37559a7ee2930002a804ad3f13", "commit_rev":
"de1590919f4aa01c7b70474c9cde733faef87596"}

[commit-bot: I haz the power, 2017-05-02 13:15:05]

Description was changed from

==========
Revert of Relanding: Fixing crash that can occur if signal is modified while
firing. (patchset #4 id:60001 of https://codereview.webrtc.org/2846593005/ )

Reason for revert:
Breaks XmppConnectionTest in Chrome.

https://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium...

Original issue's description:
> Relanding: Fixing crash that can occur if signal is modified while firing.
> 
> The crash occurs if a slot causes the very next slot in iteration order
> to be disconnected.
> 
> Relanding after fixing a race condition that this CL revealed. Previously
> the race resulted in an invalidated iterator, but now it will result in the
> iterator being modified, so TSan catches it.
> 
> BUG=webrtc:7527
> 
> Review-Url: https://codereview.webrtc.org/2846593005
> Cr-Original-Commit-Position: refs/heads/master@{#17943}
> Committed:
https://chromium.googlesource.com/external/webrtc/+/961c2adf1ea25bcc40ad64cae...
> Review-Url: https://codereview.webrtc.org/2846593005
> Cr-Commit-Position: refs/heads/master@{#17965}
> Committed:
https://chromium.googlesource.com/external/webrtc/+/fc1af0155718d029a97fddfd6...

TBR=pthatcher@webrtc.org,deadbeef@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=webrtc:7527
==========

to

==========
Revert of Relanding: Fixing crash that can occur if signal is modified while
firing. (patchset #4 id:60001 of https://codereview.webrtc.org/2846593005/ )

Reason for revert:
Breaks XmppConnectionTest in Chrome.

https://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium...

Original issue's description:
> Relanding: Fixing crash that can occur if signal is modified while firing.
> 
> The crash occurs if a slot causes the very next slot in iteration order
> to be disconnected.
> 
> Relanding after fixing a race condition that this CL revealed. Previously
> the race resulted in an invalidated iterator, but now it will result in the
> iterator being modified, so TSan catches it.
> 
> BUG=webrtc:7527
> 
> Review-Url: https://codereview.webrtc.org/2846593005
> Cr-Original-Commit-Position: refs/heads/master@{#17943}
> Committed:
https://chromium.googlesource.com/external/webrtc/+/961c2adf1ea25bcc40ad64cae...
> Review-Url: https://codereview.webrtc.org/2846593005
> Cr-Commit-Position: refs/heads/master@{#17965}
> Committed:
https://chromium.googlesource.com/external/webrtc/+/fc1af0155718d029a97fddfd6...

TBR=pthatcher@webrtc.org,deadbeef@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=webrtc:7527

Review-Url: https://codereview.webrtc.org/2859443002
Cr-Commit-Position: refs/heads/master@{#17975}
Committed:
https://chromium.googlesource.com/external/webrtc/+/de1590919f4aa01c7b70474c9...
==========

[commit-bot: I haz the power, 2017-05-02 13:15:06]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/external/webrtc/+/de1590919f4aa01c7b70474c9...