Bluetooth: macOS: DidModifyServices can happens while scanning

device/bluetooth/test/mock_bluetooth_cbcharacteristic_mac.mm

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "device/bluetooth/test/mock_bluetooth_cbcharacteristic_mac.h"
 
 #include "base/mac/foundation_util.h"
 #include "base/mac/scoped_nsobject.h"
 #include "device/bluetooth/bluetooth_gatt_characteristic.h"
 #include "device/bluetooth/test/mock_bluetooth_cbdescriptor_mac.h"
@@ skipping 171 matching lines @@
 }
 
 - (void)simulateGattCharacteristicChangedWithValue:(NSData*)value {
   _value.reset([value copy]);
   CBPeripheral* peripheral = _service.peripheral;
   [peripheral.delegate peripheral:peripheral
       didUpdateValueForCharacteristic:self.characteristic
                                 error:nil];
 }
 
-- (void)simulateDescriptorWithUUID:(CBUUID*)uuid {
+- (void)addDescriptorWithUUID:(CBUUID*)uuid {
   scoped_nsobject<MockCBDescriptor> descriptor_mock([[MockCBDescriptor alloc]
       initWithCharacteristic:self.characteristic
                       CBUUID:uuid]);
   [_simulatedDescriptors.get() addObject:descriptor_mock];
 }
 
 - (void)discoverDescriptors {
   _descriptors.reset([_simulatedDescriptors copy]);
 }
 
@@ skipping 19 matching lines @@
 
 - (NSData*)value {
   return _value.get();
 }
 
 - (BOOL)isNotifying {
   return _notifying;
 }
 
 @end