Implement WebBluetooth descriptor.writeValue()

third_party/WebKit/LayoutTests/bluetooth/script-tests/descriptor/io-op-device-disconnects-during-error.js

 'use strict';
 promise_test(
     () => {
       let val = new Uint8Array([1]);
       return setBluetoothFakeAdapter('FailingGATTOperationsAdapter')
           .then(() => requestDeviceWithKeyDown({
                   filters: [{services: [errorUUID(0xA0)]}],
                   optionalServices: [request_disconnection_service_uuid]
                 }))
           .then(device => device.gatt.connect())
           .then(gattServer => {
             let error_characteristic;
             return gattServer.getPrimaryService(errorUUID(0xA0))
                 .then(es => es.getCharacteristic(errorUUID(0xA1)))
                 .then(
                     characteristic => characteristic.getDescriptor(
                         'gatt.characteristic_user_description'))
                 .then(d => user_description = d)
                 .then(() => get_request_disconnection(gattServer))
                 .then(requestDisconnection => {
                   requestDisconnection();
                   return assert_promise_rejects_with_message(
-                      user_description.CALLS([readValue()]),
+                      user_description.CALLS([readValue()|writeValue(val)]),
                       new DOMException(
                           'GATT Server disconnected while performing a GATT operation.',
                           'NetworkError'));
                 });
           });
     },
     'Device disconnects during a FUNCTION_NAME call that fails. ' +
         'Reject with NetworkError.');