Expose TxPower for bluetooth devices during discovery

device/bluetooth/bluetooth_adapter_chromeos.cc

Index: device/bluetooth/bluetooth_adapter_chromeos.cc
diff --git a/device/bluetooth/bluetooth_adapter_chromeos.cc b/device/bluetooth/bluetooth_adapter_chromeos.cc
index 5af69c84613975d64aa0653f2182e90bdb503183..a521c8f95a2f76d1d82bab850b349196a6cc6124 100644
--- a/device/bluetooth/bluetooth_adapter_chromeos.cc
+++ b/device/bluetooth/bluetooth_adapter_chromeos.cc
@@ -428,7 +428,8 @@ void BluetoothAdapterChromeOS::DevicePropertyChanged(
       property_name == properties->trusted.name() ||
       property_name == properties->connected.name() ||
       property_name == properties->uuids.name() ||
-      property_name == properties->rssi.name())
+      property_name == properties->rssi.name() ||
+      property_name == properties->tx_power.name())
     NotifyDeviceChanged(device_chromeos);
 
   // When a device becomes paired, mark it as trusted so that the user does