base

Fix bug 2684341 Don't steal the media button event from the phone
app is the phone is ringing, even in silent mode.

Use the PhoneStateListener to know whether the phone is ringing,
as the mode is not MODE_RINGTONE when ringing in silent mode.

Change-Id: Iede350cecde0b663d50f9b4a57f9a9ef08066c0d