Revert of Override rtc::Event with Chromium's implementation

Revert of Override rtc::Event with Chromium's implementation (patchset #2 id:20001 of https://codereview.chromium.org/2975553002/ )

Reason for revert:
Reverting temporarily until the webrtc change can be rolled with it.

Original issue's description:
> Preparation of overriding WebRTC's rtc::Event with Chromium's implementation.
> This change will give WebRTC the benefits of Chromium's checks and integration with thread and sequence runners (e.g. io and waitable checks).
> 
> Followup changes include enabling the code from the WebRTC side (requires build file changes) and integrating the TaskQueue implementation in Chromium with sequence runners.
> 
> BUG=689520
> NOTRY=true
> 
> Review-Url: https://codereview.chromium.org/2975553002
> Cr-Commit-Position: refs/heads/master@{#486737}
> Committed: https://chromium.googlesource.com/chromium/src/+/07019da77f12dc06fd8a2e66061c8a79c90bc439

TBR=grunell@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=689520
Review-Url: https://codereview.chromium.org/2981863002
Cr-Commit-Position: refs/heads/master@{#486739}
Committed: https://chromium.googlesource.com/chromium/src/+/8b70da209684e205d2ca7a363887715f0c8285be

[tommi (sloooow) - chröme, 2017-07-14 11:50:41]

The CQ bit was checked by tommi@chromium.org

[tommi (sloooow) - chröme, 2017-07-14 11:50:42]

Created Revert of Override rtc::Event with Chromium's implementation

[commit-bot: I haz the power, 2017-07-14 11:50:48]

CQ is trying da patch.

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

[commit-bot: I haz the power, 2017-07-14 11:51:10]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1500033041970760, "parent_rev":
"f897be018a79d561336a04ca1f9ca4686d6d154a", "commit_rev":
"8b70da209684e205d2ca7a363887715f0c8285be"}

[commit-bot: I haz the power, 2017-07-14 11:51:23]

Description was changed from

==========
Revert of Override rtc::Event with Chromium's implementation (patchset #2
id:20001 of https://codereview.chromium.org/2975553002/ )

Reason for revert:
Reverting temporarily until the webrtc change can be rolled with it.

Original issue's description:
> Preparation of overriding WebRTC's rtc::Event with Chromium's implementation.
> This change will give WebRTC the benefits of Chromium's checks and integration
with thread and sequence runners (e.g. io and waitable checks).
> 
> Followup changes include enabling the code from the WebRTC side (requires
build file changes) and integrating the TaskQueue implementation in Chromium
with sequence runners.
> 
> BUG=689520
> NOTRY=true
> 
> Review-Url: https://codereview.chromium.org/2975553002
> Cr-Commit-Position: refs/heads/master@{#486737}
> Committed:
https://chromium.googlesource.com/chromium/src/+/07019da77f12dc06fd8a2e66061c...

TBR=grunell@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=689520
==========

to

==========
Revert of Override rtc::Event with Chromium's implementation (patchset #2
id:20001 of https://codereview.chromium.org/2975553002/ )

Reason for revert:
Reverting temporarily until the webrtc change can be rolled with it.

Original issue's description:
> Preparation of overriding WebRTC's rtc::Event with Chromium's implementation.
> This change will give WebRTC the benefits of Chromium's checks and integration
with thread and sequence runners (e.g. io and waitable checks).
> 
> Followup changes include enabling the code from the WebRTC side (requires
build file changes) and integrating the TaskQueue implementation in Chromium
with sequence runners.
> 
> BUG=689520
> NOTRY=true
> 
> Review-Url: https://codereview.chromium.org/2975553002
> Cr-Commit-Position: refs/heads/master@{#486737}
> Committed:
https://chromium.googlesource.com/chromium/src/+/07019da77f12dc06fd8a2e66061c...

TBR=grunell@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=689520

Review-Url: https://codereview.chromium.org/2981863002
Cr-Commit-Position: refs/heads/master@{#486739}
Committed:
https://chromium.googlesource.com/chromium/src/+/8b70da209684e205d2ca7a363887...
==========

[commit-bot: I haz the power, 2017-07-14 11:51:24]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/8b70da209684e205d2ca7a363887...

[Henrik Grunell, 2017-07-14 11:57:23]

lgtm