Feature Request - Add IAudioHandler

[amaitland]

CEF has added the ability to capture the audio output to a buffer. Relevant commit.

https://bitbucket.org/chromiumembedded/cef/commits/9f41a27e586a6b557fc171d2f03b332c1338e8d2?at=3683

Requires addition of a new IAudioHandler interface and ChannelLayout` enum.

[amaitland]

Initial PR at #2727 (very much a work in progress)

[amaitland]

IAudioHandler has been added, there is currently no working example as I ran out of time when writing one. The only area in question for the wrapper implementation is const float** data being mapped to IntPtr correctly. I believe it's correct though haven't been able to test.

It's important to note that the data received is RAW PCM data, you won't be able to write it directly to disk and play it in just any media player as it contains no header information.

[amaitland]

The Chromium implementation has changed so dramatically that CEF has removed support see https://bitbucket.org/chromiumembedded/cef/commits/1f893c76a97eaa88e3ff782b8e2e47dd0f5d27b2

Track https://bitbucket.org/chromiumembedded/cef/issues/2755/reimplement-audio-mirroring-for for details on when it will be reimplemented

Was removed from CefSharp in 802bb7f

[amaitland]

#3152 will track the progress of re-adding the audio handler.