bluetooth: mac: write characteristic implementation

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"
 
@@ skipping 119 matching lines @@
 }
 
 - (void)simulateReadWithValue:(NSData*)value error:(NSError*)error {
   _value.reset([value copy]);
   CBPeripheral* peripheral = _service.peripheral;
   [peripheral.delegate peripheral:peripheral
       didUpdateValueForCharacteristic:self.characteristic
                                 error:error];
 }
 
+- (void)simulateWriteWithError:(NSError*)error {
+  CBPeripheral* peripheral = _service.peripheral;
+  [peripheral.delegate peripheral:peripheral
+      didWriteValueForCharacteristic:self.characteristic
+                               error:error];
+}
+
 - (CBUUID*)UUID {
   return _UUID.get();
 }
 
 - (CBCharacteristic*)characteristic {
   return ObjCCast<CBCharacteristic>(self);
 }
 
 - (CBService*)service {
   return _service;
 }
 
 - (CBCharacteristicProperties)properties {
   return _cb_properties;
 }
 
 - (NSData*)value {
   return _value.get();
 }
 
 @end