Revert: Change VideoTrack implementation to invoke VideoTrackSourceInterface::AddOrUpdateSink on wt

Revert of Change VideoTrack implementation to invoke VideoTrackSourceInterface::AddOrUpdateSink on wt (patchset #2 id:20001 of https://codereview.webrtc.org/2964863002/ )

Reason for revert:
RemoveSink became pure virtual at the VideoTrackInterface level, which broke code that was subclassing VideoTrackInterface directly. So the CL can be re-landed without that change.

Original issue's description:
> Change VideoTrack implementation to invoke VideoTrackSourceInterface::AddOrUpdateSink on the worker thread. 
> 
> Added documentation of thread expectations for video tracks and sources to the API.
> 
> BUG=None
> 
> Review-Url: https://codereview.webrtc.org/2964863002
> Cr-Commit-Position: refs/heads/master@{#18938}
> Committed: https://chromium.googlesource.com/external/webrtc/+/f1377f722271b4b5a090d4dba10201031d31f20d

TBR=deadbeef@webrtc.org,noahric@chromium.org,yujo@chromium.org,perkj@webrtc.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=None

Review-Url: https://codereview.webrtc.org/2979493003
Cr-Commit-Position: refs/heads/master@{#18942}
Committed: https://chromium.googlesource.com/external/webrtc/+/539d104e3e8263892f2680a12c1dc1dbfb98aa4e

[mbonadei, 2017-07-10 09:08:53]

The CQ bit was checked by mbonadei@webrtc.org

[mbonadei, 2017-07-10 09:08:53]

Created Revert of Change VideoTrack implementation to invoke
VideoTrackSourceInterface::AddOrUpdateSink on wt

[commit-bot: I haz the power, 2017-07-10 09:40:55]

Description was changed from

==========
Revert of Change VideoTrack implementation to invoke
VideoTrackSourceInterface::AddOrUpdateSink on wt (patchset #2 id:20001 of
https://codereview.webrtc.org/2964863002/ )

Reason for revert:
It breaks a downstream project.

Original issue's description:
> Change VideoTrack implementation to invoke
VideoTrackSourceInterface::AddOrUpdateSink on the worker thread. 
> 
> Added documentation of thread expectations for video tracks and sources to the
API.
> 
> BUG=None
> 
> Review-Url: https://codereview.webrtc.org/2964863002
> Cr-Commit-Position: refs/heads/master@{#18938}
> Committed:
https://chromium.googlesource.com/external/webrtc/+/f1377f722271b4b5a090d4dba...

TBR=deadbeef@webrtc.org,noahric@chromium.org,yujo@chromium.org,perkj@webrtc.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=None
==========

to

==========
Revert of Change VideoTrack implementation to invoke
VideoTrackSourceInterface::AddOrUpdateSink on wt (patchset #2 id:20001 of
https://codereview.webrtc.org/2964863002/ )

Reason for revert:
It breaks a downstream project.

Original issue's description:
> Change VideoTrack implementation to invoke
VideoTrackSourceInterface::AddOrUpdateSink on the worker thread. 
> 
> Added documentation of thread expectations for video tracks and sources to the
API.
> 
> BUG=None
> 
> Review-Url: https://codereview.webrtc.org/2964863002
> Cr-Commit-Position: refs/heads/master@{#18938}
> Committed:
https://chromium.googlesource.com/external/webrtc/+/f1377f722271b4b5a090d4dba...

TBR=deadbeef@webrtc.org,noahric@chromium.org,yujo@chromium.org,perkj@webrtc.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=None

Review-Url: https://codereview.webrtc.org/2979493003
Cr-Commit-Position: refs/heads/master@{#18942}
Committed:
https://chromium.googlesource.com/external/webrtc/+/539d104e3e8263892f2680a12...
==========

[Taylor Brandstetter, 2017-07-10 17:35:33]

Description was changed from

==========
Revert of Change VideoTrack implementation to invoke
VideoTrackSourceInterface::AddOrUpdateSink on wt (patchset #2 id:20001 of
https://codereview.webrtc.org/2964863002/ )

Reason for revert:
It breaks a downstream project.

Original issue's description:
> Change VideoTrack implementation to invoke
VideoTrackSourceInterface::AddOrUpdateSink on the worker thread. 
> 
> Added documentation of thread expectations for video tracks and sources to the
API.
> 
> BUG=None
> 
> Review-Url: https://codereview.webrtc.org/2964863002
> Cr-Commit-Position: refs/heads/master@{#18938}
> Committed:
https://chromium.googlesource.com/external/webrtc/+/f1377f722271b4b5a090d4dba...

TBR=deadbeef@webrtc.org,noahric@chromium.org,yujo@chromium.org,perkj@webrtc.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=None

Review-Url: https://codereview.webrtc.org/2979493003
Cr-Commit-Position: refs/heads/master@{#18942}
Committed:
https://chromium.googlesource.com/external/webrtc/+/539d104e3e8263892f2680a12...
==========

to

==========
Revert of Change VideoTrack implementation to invoke
VideoTrackSourceInterface::AddOrUpdateSink on wt (patchset #2 id:20001 of
https://codereview.webrtc.org/2964863002/ )

Reason for revert:
RemoveSink became pure virtual at the VideoTrackInterface level, which broke
code that was subclassing VideoTrackInterface directly. So the CL can be
re-landed without that change.

Original issue's description:
> Change VideoTrack implementation to invoke
VideoTrackSourceInterface::AddOrUpdateSink on the worker thread. 
> 
> Added documentation of thread expectations for video tracks and sources to the
API.
> 
> BUG=None
> 
> Review-Url: https://codereview.webrtc.org/2964863002
> Cr-Commit-Position: refs/heads/master@{#18938}
> Committed:
https://chromium.googlesource.com/external/webrtc/+/f1377f722271b4b5a090d4dba...

TBR=deadbeef@webrtc.org,noahric@chromium.org,yujo@chromium.org,perkj@webrtc.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=None

Review-Url: https://codereview.webrtc.org/2979493003
Cr-Commit-Position: refs/heads/master@{#18942}
Committed:
https://chromium.googlesource.com/external/webrtc/+/539d104e3e8263892f2680a12...
==========

[Taylor Brandstetter, 2017-07-10 17:35:53]

Updated description with more specific revert reason.