Revert 238953 "Adding an audio-level WebRTC test to verify mutin..."

> Adding an audio-level WebRTC test to verify muting and playback.
> 
> This test uses the stats API to measure the audioOutputLevel. Since the
> content browsertests always uses fake devices we can adapt the test to
> look for that particular signal.
> 
> This test is primarily intended to run on Android but will work on 
> desktop as well. Tested by running manually on a Nexus 7 device 
> at my workstation.
> 
> BUG=325164
> 
> Review URL: https://codereview.chromium.org/101773002

TBR=phoglund@chromium.org
BUG=326338

Review URL: https://codereview.chromium.org/107443002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239065 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 239065