Added internal API to get/set the A2DP Active Device
1. Call BluetoothA2dp.setActiveDevice(BluetoothDevice device) to set
a connected A2DP device as active.
2. Listen for BluetoothA2dp.ACTION_ACTIVE_DEVICE_CHANGED intent
that will contain the latest active device (in EXTRA_DEVICE field).
If the active device could not be changed, the EXTRA_DEVICE
field could be null.
3. If setActiveDevice() is NOT in-progress, BluetoothA2dp.getActiveDevice()
can be used. If setActiveDevice() is in-progress, the result is undefined.
4. BluetoothA2dp.setActiveDevice() could be called by some other parts of
the system, so interested parties should always listen for
BluetoothA2dp.ACTION_ACTIVE_DEVICE_CHANGED intents and prepared
for active device updates.
Bug:
71555243
Test: Manual
Change-Id: Ia25465e17a4539e940d09523cb621b230abd31e3