Expose device RSSI and Tx power via the chrome.bluetooth API.

device/bluetooth/bluetooth_device_chromeos.cc

Index: device/bluetooth/bluetooth_device_chromeos.cc
diff --git a/device/bluetooth/bluetooth_device_chromeos.cc b/device/bluetooth/bluetooth_device_chromeos.cc
index b5f73862fce8a07d4bbc35f7323a976539f4e89b..0b1be8d8b83f3cfb7dc8b1b0f352097f1b4c3b8b 100644
--- a/device/bluetooth/bluetooth_device_chromeos.cc
+++ b/device/bluetooth/bluetooth_device_chromeos.cc
@@ -212,6 +212,11 @@ uint16 BluetoothDeviceChromeOS::GetDeviceID() const {
   return device_id;
 }
 
+int BluetoothDeviceChromeOS::GetRSSI() const {
+  NOTIMPLEMENTED();
+  return 0;
+}
+
 bool BluetoothDeviceChromeOS::IsPaired() const {
   BluetoothDeviceClient::Properties* properties =
       DBusThreadManager::Get()->GetBluetoothDeviceClient()->