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

device/bluetooth/bluetooth_classic_device_mac.mm

Index: device/bluetooth/bluetooth_classic_device_mac.mm
diff --git a/device/bluetooth/bluetooth_classic_device_mac.mm b/device/bluetooth/bluetooth_classic_device_mac.mm
index 985596ecfc59873e8797f52d9690489597abda9c..dfa8a7e87a0860a3b399c2a9626be3ac14c1ae66 100644
--- a/device/bluetooth/bluetooth_classic_device_mac.mm
+++ b/device/bluetooth/bluetooth_classic_device_mac.mm
@@ -145,13 +145,13 @@ BluetoothDevice::UUIDList BluetoothClassicDeviceMac::GetUUIDs() const {
   return uuids;
 }
 
-int16_t BluetoothClassicDeviceMac::GetInquiryRSSI() const {
-  return kUnknownPower;
+int8_t BluetoothClassicDeviceMac::GetInquiryRSSI() const {
+  return kUnknownRSSI;
 }
 
-int16_t BluetoothClassicDeviceMac::GetInquiryTxPower() const {
+int8_t BluetoothClassicDeviceMac::GetInquiryTxPower() const {
   NOTIMPLEMENTED();
-  return kUnknownPower;
+  return kUnknownTxPower;
 }
 
 bool BluetoothClassicDeviceMac::ExpectingPinCode() const {
@@ -181,7 +181,7 @@ void BluetoothClassicDeviceMac::GetConnectionInfo(
   // 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;
+    connection_info.rssi = kUnknownRSSI;
 
   connection_info.transmit_power =
       GetHostTransmitPower(kReadCurrentTransmitPowerLevel);
@@ -266,7 +266,7 @@ int BluetoothClassicDeviceMac::GetHostTransmitPower(
                                                        inType:
                                         outTransmitPowerLevel:);
   if (![controller respondsToSelector:selector])
-    return kUnknownPower;
+    return kUnknownTxPower;
 
   BluetoothHCITransmitPowerLevel power_level;
   IOReturn result =
@@ -274,7 +274,7 @@ int BluetoothClassicDeviceMac::GetHostTransmitPower(
                                               inType:power_level_type
                                outTransmitPowerLevel:&power_level];
   if (result != kIOReturnSuccess)
-    return kUnknownPower;
+    return kUnknownTxPower;
 
   return power_level;
 }