audio framework: manage stream volume per device

Improve volume management by keeping track of volume for each type
of device independently.
Volume for each stream (MUSIC, RINGTONE, VOICE_CALL...) is now maintained
per device.

The main changes are:
- AudioService now keeps tracks of stream volumes per device:
 volume indexes are kept in a HashMap < device , index>.
 active device is queried from policy manager when a volume change request
 is received
 initalization, mute and unmute happen on all device simultaneously
- Settings: suffixes is added to volume keys to store each device
volume independently.
- AudioSystem/AudioPolicyService/AudioPolicyInterface: added a device argument
to setStreamVolumeIndex() and getStreamVolumeIndex() to address each
device independently.
- AudioPolicyManagerBase: keep track of stream volumes for each device
and apply volume according to current device selection.

Change-Id: I61ef1c45caadca04d16363bca4140e0f81901b3f
diff --git a/include/media/AudioSystem.h b/include/media/AudioSystem.h
index e49d8f5..13beaa5 100644
--- a/include/media/AudioSystem.h
+++ b/include/media/AudioSystem.h
@@ -170,8 +170,12 @@
     static status_t initStreamVolume(audio_stream_type_t stream,
                                       int indexMin,
                                       int indexMax);
-    static status_t setStreamVolumeIndex(audio_stream_type_t stream, int index);
-    static status_t getStreamVolumeIndex(audio_stream_type_t stream, int *index);
+    static status_t setStreamVolumeIndex(audio_stream_type_t stream,
+                                         int index,
+                                         audio_devices_t device);
+    static status_t getStreamVolumeIndex(audio_stream_type_t stream,
+                                         int *index,
+                                         audio_devices_t device);
 
     static uint32_t getStrategyForStream(audio_stream_type_t stream);
     static uint32_t getDevicesForStream(audio_stream_type_t stream);