Revert of MediaCaptureFromElement: add support for audio captureStream(). (patchset #6 id:760001 of https://codereview.chromium.org/1599533003/ )

Reason for revert:
The layout tests added are flakily crashing on various bots,

 https://build.chromium.org/p/chromium.webkit/builders/WebKit%20Linux%20Leak/builds/19683
 https://build.chromium.org/p/chromium.webkit/builders/WebKit%20Linux/builds/65000

Original issue's description:
> MediaCaptureFromElement: add support for audio captureStream().
>
> This CL extends support for capturing the audio part of
> a <video> or <audio> tags ( "capture" here means creating
> a MediaStream out of the HTMLElement)
>
> It introduces an HtmlAudioCapturerSource is-a AudioCapturerSource
> wrapped into an ExternalMediaStreamAudioSource to produce data
> towards the audio track.
>
> HtmlAudioCapturerSource also plugs into the
> WebMediaPlayer's WebAudioSourceProviderImpl to get
> a copy of the audio being rendered.
>
> Unit tests are added, and the existing LayouTests
> revamped (and split into several files for clarity).
>
> BUG=569976, 575492
>
> TEST= run chromium with
>  --enable-blink-features=MediaCaptureFromVideo
>  against e.g.
> https://rawgit.com/Miguelao/demos/master/videoelementcapture.html
>
> Committed: https://crrev.com/77d0d446e58afbf7fab215113fcf9fe9c97e94e3
> Cr-Commit-Position: refs/heads/master@{#395205}

TBR=esprehn@chromium.org,avi@chromium.org,dalecurtis@chromium.org,haraken@chromium.org,miu@chromium.org,mcasas@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=569976, 575492
NOTRY=true

Review-Url: https://codereview.chromium.org/2007433002
Cr-Commit-Position: refs/heads/master@{#395298}
15 files changed