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

content/common/bluetooth/bluetooth_device.h

Index: content/common/bluetooth/bluetooth_device.h
diff --git a/content/common/bluetooth/bluetooth_device.h b/content/common/bluetooth/bluetooth_device.h
index 535f13c15ee54084cb8082726111f45208024417..8bb822f804cc8e1d0b9b355add47475f940cda04 100644
--- a/content/common/bluetooth/bluetooth_device.h
+++ b/content/common/bluetooth/bluetooth_device.h
@@ -28,13 +28,6 @@ struct CONTENT_EXPORT BluetoothDevice {
 
   static std::vector<std::string> UUIDsFromBluetoothUUIDs(
       const device::BluetoothDevice::UUIDList& uuid_list);
-  // 127 is used as Unknown Power. According to the Bluetooth spec valid powers
-  // are between [-127, 127]. Anything outside this range will be considered
-  // Unknown Power.
-  static int8_t ValidatePower(int16_t power);
-  // TODO(ortuno): RSSI Unknown and Tx Power Unknown should have different
-  // values. Add kUnknownTxPower when implemented: http://crbug.com/551572
-  const static int8_t kUnknownPower = 127;
 
   std::string id;
   base::string16 name;