device/bluetooth: Implement Unregister() of BlueotoothAudioSinkChromeOS and disconnection-related c…

device/bluetooth/bluetooth_audio_sink.cc

Index: device/bluetooth/bluetooth_audio_sink.cc
diff --git a/device/bluetooth/bluetooth_audio_sink.cc b/device/bluetooth/bluetooth_audio_sink.cc
index 4c9435e9bd5f1771a146583becb72ed2c1aa12cf..75247fe08bec0ece3cd867f78fe8a16b8ab35908 100644
--- a/device/bluetooth/bluetooth_audio_sink.cc
+++ b/device/bluetooth/bluetooth_audio_sink.cc
@@ -27,6 +27,9 @@ namespace {
 
 namespace device {
 
+// static
+const uint16_t BluetoothAudioSink::kInvalidVolume = 128;
+
 BluetoothAudioSink::Options::Options() : codec(kDefaultCodec) {
   capabilities.assign(kDefaultCapabilities,
                       kDefaultCapabilities + sizeof(kDefaultCapabilities));