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

device/bluetooth/bluetooth_classic_device_mac.mm

 // 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/bluetooth_classic_device_mac.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/hash.h"
@@ skipping 127 matching lines @@
     if ([service_class_data getTypeDescriptor] ==
         kBluetoothSDPDataElementTypeDataElementSequence) {
       BluetoothUUID uuid = ExtractUuid(service_class_data);
       if (uuid.IsValid())
         uuids.push_back(uuid);
     }
   }
   return uuids;
 }
 
-int16_t BluetoothClassicDeviceMac::GetInquiryRSSI() const {
-  return kUnknownPower;
+base::Optional<int8_t> BluetoothClassicDeviceMac::GetInquiryRSSI() const {
+  return base::Optional<int8_t>();

[scheib, 2016/05/07 02:06:52]

return nullopt;

 }
 
-int16_t BluetoothClassicDeviceMac::GetInquiryTxPower() const {
+base::Optional<int8_t> BluetoothClassicDeviceMac::GetInquiryTxPower() const {
   NOTIMPLEMENTED();
-  return kUnknownPower;
+  return base::Optional<int8_t>();
 }
 
 bool BluetoothClassicDeviceMac::ExpectingPinCode() const {
   NOTIMPLEMENTED();
   return false;
 }
 
 bool BluetoothClassicDeviceMac::ExpectingPasskey() const {
   NOTIMPLEMENTED();
   return false;
 }
 
 bool BluetoothClassicDeviceMac::ExpectingConfirmation() const {
   NOTIMPLEMENTED();
   return false;
 }
 
 void BluetoothClassicDeviceMac::GetConnectionInfo(
     const ConnectionInfoCallback& callback) {
   ConnectionInfo connection_info;
   if (![device_ isConnected]) {
     callback.Run(connection_info);
     return;
   }
 
-  connection_info.rssi = [device_ rawRSSI];
+  BluetoothHCIRSSIValue rssi = [device_ rawRSSI];
+
   // The API guarantees that +127 is returned in case the RSSI is not readable:
   // http://goo.gl/bpURYv
-  if (connection_info.rssi == 127)
-    connection_info.rssi = kUnknownPower;
+  if (rssi == 127)
+    connection_info.rssi = base::make_optional(rssi);

[scheib, 2016/05/07 02:06:52]

In the event rssi is 127 we want to use nullopt, else make_optional(rssi); I
think:
  connection_info.rssi = (rssi == 127) ? base::nullopt :
base::make_optional(rssi);

 
   connection_info.transmit_power =
       GetHostTransmitPower(kReadCurrentTransmitPowerLevel);
   connection_info.max_transmit_power =
       GetHostTransmitPower(kReadMaximumTransmitPowerLevel);
 
   callback.Run(connection_info);
 }
 
 void BluetoothClassicDeviceMac::Connect(
@@ skipping 54 matching lines @@
     const GattConnectionCallback& callback,
     const ConnectErrorCallback& error_callback) {
   // TODO(armansito): Implement.
   error_callback.Run(ERROR_UNSUPPORTED_DEVICE);
 }
 
 NSDate* BluetoothClassicDeviceMac::GetLastUpdateTime() const {
   return [device_ getLastInquiryUpdate];
 }
 
-int BluetoothClassicDeviceMac::GetHostTransmitPower(
+base::Optional<int8_t> BluetoothClassicDeviceMac::GetHostTransmitPower(
     BluetoothHCITransmitPowerLevelType power_level_type) const {
   IOBluetoothHostController* controller =
       [IOBluetoothHostController defaultController];
 
   // Bail if the undocumented API is unavailable on this machine.
   SEL selector = @selector(BluetoothHCIReadTransmitPowerLevel:
                                                        inType:
                                         outTransmitPowerLevel:);
   if (![controller respondsToSelector:selector])
-    return kUnknownPower;
+    return base::nullopt;
 
   BluetoothHCITransmitPowerLevel power_level;
   IOReturn result =
       [controller BluetoothHCIReadTransmitPowerLevel:[device_ connectionHandle]
                                               inType:power_level_type
                                outTransmitPowerLevel:&power_level];
   if (result != kIOReturnSuccess)
-    return kUnknownPower;
+    return base::nullopt;
 
-  return power_level;
+  return base::make_optional(power_level);
 }
 
 // static
 std::string BluetoothClassicDeviceMac::GetDeviceAddress(
     IOBluetoothDevice* device) {
   return CanonicalizeAddress(base::SysNSStringToUTF8([device addressString]));
 }
 
 }  // namespace device