audioflinger: forward device change to effects in direct thread

Device change during offload playback is not informed to effect chain
which causes effects still work on unexpected output devices. Add device
change notification in direct output thread.

CRs-Fixed: 630408

Change-Id: I094a99bdf540479cee2fca6614ec35c2fa7d6046
AudioTrack: When paused, return cached playback position

An offload output can be re-used between two audio tracks having
the same configuration. A timestamp query for a paused track
while the other is running would return an incorrect time.
To fix this, cache the playback position on a pause() and return
this time when requested until the track is resumed.

CRs-Fixed: 612943

Change-Id: I54b5a851ee3fa2ceadc37e3f5c6af4f37b8f404a
audio: mute duration at the beginning of recording

-AudioSource mutes for predefined duration (kAutoRampStartUs)
 at the beginning of a recording. Current kAutoRampStartUs
 is not sufficient to mute the shutter sound click on
 B-Family devices. Sometime shutter sound is getting recorded
 with the current kAutoRampStartUs.

-Issue with calculating muteDuration from getOutputLatency is,
 more delay is getting added for Bt(~1 sec) which is really not
 required.

-Fix is to use constant mute delay which is appropriate

Change-Id: Ied20dc44c56cc74c74fb001383d3c533cb54b632
CRs-Fixed: 636491