bluetooth: Change GetInquiryTxPower and GetInquiryRSSI to return optional.

device/bluetooth/bluetooth_device_win.cc

Index: device/bluetooth/bluetooth_device_win.cc
diff --git a/device/bluetooth/bluetooth_device_win.cc b/device/bluetooth/bluetooth_device_win.cc
index f71c1372891f7d474ddd2445d8b630cc132aa9f0..9436651ccbc9a86a86a5a290ae35dc6b5f206f07 100644
--- a/device/bluetooth/bluetooth_device_win.cc
+++ b/device/bluetooth/bluetooth_device_win.cc
@@ -116,13 +116,16 @@ BluetoothDevice::UUIDList BluetoothDeviceWin::GetUUIDs() const {
   return uuids_;
 }
 
-int16_t BluetoothDeviceWin::GetInquiryRSSI() const {
-  return kUnknownPower;
+base::Optional<int8_t> BluetoothDeviceWin::GetInquiryRSSI() const {
+  // In windows, we can only get connected devices and connected
+  // devices don't have an Inquiry RSSI.
+  return base::nullopt;
 }
 
-int16_t BluetoothDeviceWin::GetInquiryTxPower() const {
-  NOTIMPLEMENTED();
-  return kUnknownPower;
+base::Optional<int8_t> BluetoothDeviceWin::GetInquiryTxPower() const {
+  // In windows, we can only get connected devices and connected
+  // devices don't have an Inquiry Tx Power.
+  return base::nullopt;
 }
 
 bool BluetoothDeviceWin::ExpectingPinCode() const {