Fix double StopStream() calls during wedge fix.

Whoops.  The wedge fix ignored start / stop status when stopping
streams which leads to heap corruption when the underlying dispatcher
tries to stop a stream it can't find in the audio stream map.

BUG=326656
TEST=new unittest
NOTRY=true

Review URL: https://codereview.chromium.org/109113002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239342 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 239342