Don't automatically change the audio focus when
the audio mode changes. This is best handled by the
applications that change the audio mode so they
can address their usecases as they please (for
instance to define the behavior when switching calls).
Replaced the implicit "mode to focus" behavior with
two methods to request and abandon audio focus. These
methods are only to be used by the framework, and maintain
the logic in AudioService to prevent other apps to request
audio focus during a call.
A susequent change will update com.android.internal.telephony.CallManager
to take advantage of these two methods.
Change-Id: If84ebd508e985083e8cac82ece44940c72b5c669
4dd3674e51