bluetooth: Return int8_t and use -128 for unknown tx power.

extensions/browser/api/bluetooth/bluetooth_api_utils.cc

Index: extensions/browser/api/bluetooth/bluetooth_api_utils.cc
diff --git a/extensions/browser/api/bluetooth/bluetooth_api_utils.cc b/extensions/browser/api/bluetooth/bluetooth_api_utils.cc
index 1b0c61e64e886010ca239c5f866160f168b9f775..62a5b8eee63a5a83cab42e278dadb8a23a3cd1fd 100644
--- a/extensions/browser/api/bluetooth/bluetooth_api_utils.cc
+++ b/extensions/browser/api/bluetooth/bluetooth_api_utils.cc
@@ -121,13 +121,13 @@ void BluetoothDeviceToApiDevice(const device::BluetoothDevice& device,
     string_uuids->push_back(iter->canonical_value());
   out->uuids.reset(string_uuids);
 
-  if (device.GetInquiryRSSI() != device::BluetoothDevice::kUnknownPower)
-    out->inquiry_rssi.reset(new int(device.GetInquiryRSSI()));
+  if (device.GetInquiryRSSI())
+    out->inquiry_rssi.reset(new int(device.GetInquiryRSSI().value()));
   else
     out->inquiry_rssi.reset();
 
-  if (device.GetInquiryTxPower() != device::BluetoothDevice::kUnknownPower)
-    out->inquiry_tx_power.reset(new int(device.GetInquiryTxPower()));
+  if (device.GetInquiryTxPower())
+    out->inquiry_tx_power.reset(new int(device.GetInquiryTxPower().value()));
   else
     out->inquiry_tx_power.reset();
 }