Read characteristic implementation on macOS

device/bluetooth/bluetooth_device_mac.h

Index: device/bluetooth/bluetooth_device_mac.h
diff --git a/device/bluetooth/bluetooth_device_mac.h b/device/bluetooth/bluetooth_device_mac.h
index 0124eac3d7f793e9981a8bb7000afc0fe46a0989..3ebcec8a691de0db069c9bd1f344b61a4be37c69 100644
--- a/device/bluetooth/bluetooth_device_mac.h
+++ b/device/bluetooth/bluetooth_device_mac.h
@@ -7,6 +7,7 @@
 
 #include "base/macros.h"
 #include "device/bluetooth/bluetooth_device.h"
+#include "device/bluetooth/bluetooth_gatt_service.h"
 
 @class NSDate;
 
@@ -27,6 +28,10 @@ class DEVICE_BLUETOOTH_EXPORT BluetoothDeviceMac : public BluetoothDevice {
       BluetoothDevice::ConnectErrorCode error_code);
   static BluetoothDevice::ConnectErrorCode GetConnectErrorCodeFromNSError(
       NSError* error);
+  static NSError* GetNSErrorFromGattErrorCode(
+      BluetoothGattService::GattErrorCode error_code);
+  static BluetoothGattService::GattErrorCode GetGattErrorCodeFromNSError(
+      NSError* error);
 
  protected:
   BluetoothDeviceMac(BluetoothAdapterMac* adapter);