Fix a following build error:

In file included from ../../3rdparty/chromium/device/bluetooth/bluetooth_remote_gatt_characteristic_mac.mm:7:
In file included from ../../3rdparty/chromium/base/bind.h:8:
../../3rdparty/chromium/base/bind_internal.h:214:31: error: cannot initialize a parameter of type 'NSError *' with an lvalue of type 'const long'
    return (receiver.*method)(std::forward<RunArgs>(args)...);
                              ^~~~~~~~~~~~~~~~~~~~~~~~~~~
../../3rdparty/chromium/base/bind_internal.h:285:20: note: in instantiation of function template specialization 'base::internal::FunctorTraits<void (device::BluetoothRemoteGat
tCharacteristicMac::*)(NSError *), void>::Invoke<device::BluetoothRemoteGattCharacteristicMac *, const long &>' requested here
    return Traits::Invoke(std::forward<Functor>(functor),
                   ^
../../3rdparty/chromium/base/bind_internal.h:361:43: note: in instantiation of function template specialization 'base::internal::InvokeHelper<false, void>::MakeItSo<void (devi
ce::BluetoothRemoteGattCharacteristicMac::*const &)(NSError *), device::BluetoothRemoteGattCharacteristicMac *, const long &>' requested here
    return InvokeHelper<is_weak_call, R>::MakeItSo(
                                          ^
../../3rdparty/chromium/base/bind_internal.h:339:12: note: in instantiation of function template specialization 'base::internal::Invoker<base::internal::BindState<void (device::BluetoothRemoteGattCharacteristicMac::*)(NSError *), base::internal::UnretainedWrapper<device::BluetoothRemoteGattCharacteristicMac>, long>, void ()>::RunImpl<void (device::BluetoothRemoteGattCharacteristicMac::*const &)(NSError *), const std::__1::tuple<base::internal::UnretainedWrapper<device::BluetoothRemoteGattCharacteristicMac>, long> &, 0, 1>' requested here
    return RunImpl(storage->functor_,
           ^
../../3rdparty/chromium/base/bind.h:62:45: note: in instantiation of member function 'base::internal::Invoker<base::internal::BindState<void (device::BluetoothRemoteGattCharacteristicMac::*)(NSError *), base::internal::UnretainedWrapper<device::BluetoothRemoteGattCharacteristicMac>, long>, void ()>::Run' requested here
  PolymorphicInvoke invoke_func = &Invoker::Run;
                                            ^
../../3rdparty/chromium/base/bind.h:77:10: note: in instantiation of function template specialization 'base::BindRepeating<void (device::BluetoothRemoteGattCharacteristicMac::*)(NSError *), base::internal::UnretainedWrapper<device::BluetoothRemoteGattCharacteristicMac>, long>' requested here
  return BindRepeating(std::forward<Functor>(functor),
         ^
../../3rdparty/chromium/device/bluetooth/bluetooth_remote_gatt_characteristic_mac.mm:241:15: note: in instantiation of function template specialization 'base::Bind<void (device::BluetoothRemoteGattCharacteristicMac::*)(NSError *), base::internal::UnretainedWrapper<device::BluetoothRemoteGattCharacteristicMac>, long>' requested here
        base::Bind(&BluetoothRemoteGattCharacteristicMac::DidWriteValue,

--- a/src/3rdparty/chromium/device/bluetooth/bluetooth_remote_gatt_characteristic_mac.mm
+++ b/src/3rdparty/chromium/device/bluetooth/bluetooth_remote_gatt_characteristic_mac.mm
@@ -239,7 +239,7 @@ void BluetoothRemoteGattCharacteristicMac::WriteRemoteCharacteristic(
     base::ThreadTaskRunnerHandle::Get()->PostTask(
         FROM_HERE,
         base::Bind(&BluetoothRemoteGattCharacteristicMac::DidWriteValue,
-                   base::Unretained(this), nil));
+                   base::Unretained(this), nullptr));
   }
 }