RELAND: MediaStream audio object graph untangling and clean-ups.

RELAND: MediaStream audio object graph untangling and clean-ups.

This is a re-land of https://codereview.chromium.org/1721273002 with
the signaling thread check in WebRtcLocalAudioTrackAdapter::Create()
reverted back to the way it was.  This is needed because the layout
tests do not run in a full browser environment where the WebRTC
signaling thread is present.

------------------ORIGINAL DESCRIPTION FOLLOWS------------------

This change consists of a number of "clean-up" changes that are being
done to make the soon-upcoming refactoring of these classes go much more
smoothly.  These are:

1. Public content MediaStreamApi functions cleaned up.  Removed
"duplicated" functions that don't really do the same thing.  Removed
hard-coded audio parameters from AddAudioTrackToMediaStream().

2. Eliminated ref-counting of WebRtcAudioCapturer and
WebAudioCaptureSource.  Removed unnecessary references to these from
WebRtcLocalAudioTrack.  Not only did this improve encapsulation of some
code, but it also allowed for the removal of several dozen lines of
"dead weight" testing set-upcode throughout the directory.

3. Renamed MediaStreamAudioTrack::GetTrack() method to From(), to be
consistent with how this pattern is used in other parts of libcontent,
and added a MediaStreamAudioSource::From().

4. Moved audio level calculations out of WebRtcLocalAudioTrack and into
WebRtcAudioCapturer.  This way, when multiple tracks are present, the
calculation is only being done once on the same audio.

5. Eliminated call to WebRtcCapturer::Stop() from
WebRtcAudioDeviceImpl::Terminate(), which are each supposed to run on
different threads.  From testing, DCHECKs should have been firing, but
weren't, so the Terminate() method seems to be dead code.

6. Miscellaneous other "compaction" and comment updates.

BUG=577881, 577874
TBR=jochen@chromium.org,finnur@chromium.org,o1ka@chromium.org,tommi@chromium.org,peter@chromium.org,sof@chromium.org

Committed: https://crrev.com/cfbc8cb058dcc6cf88f1c4d70c8eb76652c39123
Cr-Commit-Position: refs/heads/master@{#380214}

[miu, 2016-03-09 20:57:12]

Confirmed layout tests are passing now.

[miu, 2016-03-09 20:57:17]

The CQ bit was checked by miu@chromium.org

[commit-bot: I haz the power, 2016-03-09 20:59:04]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1780743002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1780743002/20001

[commit-bot: I haz the power, 2016-03-09 21:09:23]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-03-09 21:11:09]

Description was changed from

==========
RELAND: MediaStream audio object graph untangling and clean-ups.

This is a re-land of https://codereview.chromium.org/1721273002 with
the signaling thread check in WebRtcLocalAudioTrackAdapter::Create()
reverted back to the way it was.  This is needed because the layout
tests do not run in a full browser environment where the WebRTC
signaling thread is present.

------------------ORIGINAL DESCRIPTION FOLLOWS------------------

This change consists of a number of "clean-up" changes that are being
done to make the soon-upcoming refactoring of these classes go much more
smoothly.  These are:

1. Public content MediaStreamApi functions cleaned up.  Removed
"duplicated" functions that don't really do the same thing.  Removed
hard-coded audio parameters from AddAudioTrackToMediaStream().

2. Eliminated ref-counting of WebRtcAudioCapturer and
WebAudioCaptureSource.  Removed unnecessary references to these from
WebRtcLocalAudioTrack.  Not only did this improve encapsulation of some
code, but it also allowed for the removal of several dozen lines of
"dead weight" testing set-upcode throughout the directory.

3. Renamed MediaStreamAudioTrack::GetTrack() method to From(), to be
consistent with how this pattern is used in other parts of libcontent,
and added a MediaStreamAudioSource::From().

4. Moved audio level calculations out of WebRtcLocalAudioTrack and into
WebRtcAudioCapturer.  This way, when multiple tracks are present, the
calculation is only being done once on the same audio.

5. Eliminated call to WebRtcCapturer::Stop() from
WebRtcAudioDeviceImpl::Terminate(), which are each supposed to run on
different threads.  From testing, DCHECKs should have been firing, but
weren't, so the Terminate() method seems to be dead code.

6. Miscellaneous other "compaction" and comment updates.

BUG=577881, 577874
TBR=jochen@chromium.org,finnur@chromium.org,o1ka@chromium.org,tommi@chromium....
==========

to

==========
RELAND: MediaStream audio object graph untangling and clean-ups.

This is a re-land of https://codereview.chromium.org/1721273002 with
the signaling thread check in WebRtcLocalAudioTrackAdapter::Create()
reverted back to the way it was.  This is needed because the layout
tests do not run in a full browser environment where the WebRTC
signaling thread is present.

------------------ORIGINAL DESCRIPTION FOLLOWS------------------

This change consists of a number of "clean-up" changes that are being
done to make the soon-upcoming refactoring of these classes go much more
smoothly.  These are:

1. Public content MediaStreamApi functions cleaned up.  Removed
"duplicated" functions that don't really do the same thing.  Removed
hard-coded audio parameters from AddAudioTrackToMediaStream().

2. Eliminated ref-counting of WebRtcAudioCapturer and
WebAudioCaptureSource.  Removed unnecessary references to these from
WebRtcLocalAudioTrack.  Not only did this improve encapsulation of some
code, but it also allowed for the removal of several dozen lines of
"dead weight" testing set-upcode throughout the directory.

3. Renamed MediaStreamAudioTrack::GetTrack() method to From(), to be
consistent with how this pattern is used in other parts of libcontent,
and added a MediaStreamAudioSource::From().

4. Moved audio level calculations out of WebRtcLocalAudioTrack and into
WebRtcAudioCapturer.  This way, when multiple tracks are present, the
calculation is only being done once on the same audio.

5. Eliminated call to WebRtcCapturer::Stop() from
WebRtcAudioDeviceImpl::Terminate(), which are each supposed to run on
different threads.  From testing, DCHECKs should have been firing, but
weren't, so the Terminate() method seems to be dead code.

6. Miscellaneous other "compaction" and comment updates.

BUG=577881, 577874
TBR=jochen@chromium.org,finnur@chromium.org,o1ka@chromium.org,tommi@chromium....

Committed: https://crrev.com/cfbc8cb058dcc6cf88f1c4d70c8eb76652c39123
Cr-Commit-Position: refs/heads/master@{#380214}
==========

[commit-bot: I haz the power, 2016-03-09 21:11:11]

Patchset 2 (id:??) landed as
https://crrev.com/cfbc8cb058dcc6cf88f1c4d70c8eb76652c39123
Cr-Commit-Position: refs/heads/master@{#380214}