Notify the BluetoothAdapter::Observer when a bluetooth peripheral disconnects on Android and Mac.

device/bluetooth/bluetooth_adapter.cc

Index: device/bluetooth/bluetooth_adapter.cc
diff --git a/device/bluetooth/bluetooth_adapter.cc b/device/bluetooth/bluetooth_adapter.cc
index 6153a12d05a53fd9d1da2685feeac66c63c8c6f2..210eadbe35e77cc7fe4c53ea141666f67b7ce892 100644
--- a/device/bluetooth/bluetooth_adapter.cc
+++ b/device/bluetooth/bluetooth_adapter.cc
@@ -164,6 +164,14 @@ void BluetoothAdapter::NotifyAdapterStateChanged(bool powered) {
                     AdapterPoweredChanged(this, powered));
 }
 
+void BluetoothAdapter::NotifyDeviceChanged(BluetoothDevice* device) {
+  DCHECK(device);
+  DCHECK_EQ(device->GetAdapter(), this);
+
+  FOR_EACH_OBSERVER(BluetoothAdapter::Observer, observers_,
+                    DeviceChanged(this, device));
+}
+
 #if defined(OS_CHROMEOS) || defined(OS_LINUX)
 void BluetoothAdapter::NotifyDevicePairedChanged(BluetoothDevice* device,
                                                  bool new_paired_status) {