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

device/bluetooth/dbus/bluetooth_device_client.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "device/bluetooth/dbus/bluetooth_device_client.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/macros.h"
+#include "base/optional.h"
 #include "base/stl_util.h"
 #include "dbus/bus.h"
 #include "dbus/message.h"
 #include "dbus/object_manager.h"
 #include "dbus/object_proxy.h"
 #include "third_party/cros_system_api/dbus/service_constants.h"
 
 namespace bluez {
 
-namespace {
-
-// Value returned for the the RSSI or TX power if it cannot be read.
-const int kUnknownPower = 127;
-
-}  // namespace
-
 const char BluetoothDeviceClient::kNoResponseError[] =
     "org.chromium.Error.NoResponse";
 const char BluetoothDeviceClient::kUnknownDeviceError[] =
     "org.chromium.Error.UnknownDevice";
 
 BluetoothDeviceClient::Properties::Properties(
     dbus::ObjectProxy* object_proxy,
     const std::string& interface_name,
     const PropertyChangedCallback& callback)
     : dbus::PropertySet(object_proxy, interface_name, callback) {
@@ skipping 277 matching lines @@
 
   // Called when a response for successful method call is received.
   void OnSuccess(const base::Closure& callback, dbus::Response* response) {
     DCHECK(response);
     callback.Run();
   }
 
   // Called when a response for the GetConnInfo method is received.
   void OnGetConnInfoSuccess(const ConnInfoCallback& callback,
                             dbus::Response* response) {
-    int16_t rssi = kUnknownPower;
-    int16_t transmit_power = kUnknownPower;
-    int16_t max_transmit_power = kUnknownPower;
-
     if (!response) {
       LOG(ERROR) << "GetConnInfo succeeded, but no response received.";
-      callback.Run(rssi, transmit_power, max_transmit_power);
+      callback.Run(base::nullopt /* rssi */, base::nullopt /* transmit_power */,
+                   base::nullopt /* max_tx_power */);
       return;
     }
 
+    int16_t rssi;
+    int16_t transmit_power;
+    int16_t max_transmit_power;
+
     dbus::MessageReader reader(response);
     if (!reader.PopInt16(&rssi) || !reader.PopInt16(&transmit_power) ||
         !reader.PopInt16(&max_transmit_power)) {
       LOG(ERROR) << "Arguments for GetConnInfo invalid.";
     }
-    callback.Run(rssi, transmit_power, max_transmit_power);
+    callback.Run(base::make_optional(rssi), base::make_optional(transmit_power),
+                 base::make_optional(max_transmit_power));
   }
 
   // Called when a response for a failed method call is received.
   void OnError(const ErrorCallback& error_callback,
                dbus::ErrorResponse* response) {
     // Error response has optional error message argument.
     std::string error_name;
     std::string error_message;
     if (response) {
       dbus::MessageReader reader(response);
@@ skipping 22 matching lines @@
 
 BluetoothDeviceClient::BluetoothDeviceClient() {}
 
 BluetoothDeviceClient::~BluetoothDeviceClient() {}
 
 BluetoothDeviceClient* BluetoothDeviceClient::Create() {
   return new BluetoothDeviceClientImpl();
 }
 
 }  // namespace bluez