Bluetooth: macOS: Implementing read/write for descriptors

device/bluetooth/test/mock_bluetooth_cbcharacteristic_mac.mm

Index: device/bluetooth/test/mock_bluetooth_cbcharacteristic_mac.mm
diff --git a/device/bluetooth/test/mock_bluetooth_cbcharacteristic_mac.mm b/device/bluetooth/test/mock_bluetooth_cbcharacteristic_mac.mm
index 2cc9eb7be148850b3e66989560e7438f8e7aa607..1cf1d1838cf7e6c26e80b915afbc2ab6222bf371 100644
--- a/device/bluetooth/test/mock_bluetooth_cbcharacteristic_mac.mm
+++ b/device/bluetooth/test/mock_bluetooth_cbcharacteristic_mac.mm
@@ -96,7 +96,7 @@ CBCharacteristicProperties GattCharacteristicPropertyToCBCharacteristicProperty(
   CBCharacteristicProperties _cb_properties;
   scoped_nsobject<NSMutableArray> _simulatedDescriptors;
   scoped_nsobject<NSArray> _descriptors;
-  scoped_nsobject<NSData> _value;
+  scoped_nsobject<NSObject> _value;
   BOOL _notifying;
 }
 @end
@@ -134,7 +134,7 @@ CBCharacteristicProperties GattCharacteristicPropertyToCBCharacteristicProperty(
   return [super isKindOfClass:aClass];
 }
 
-- (void)simulateReadWithValue:(NSData*)value error:(NSError*)error {
+- (void)simulateReadWithValue:(id)value error:(NSError*)error {
   _value.reset([value copy]);
   CBPeripheral* peripheral = _service.peripheral;
   [peripheral.delegate peripheral:peripheral
@@ -220,7 +220,7 @@ CBCharacteristicProperties GattCharacteristicPropertyToCBCharacteristicProperty(
   return _descriptors;
 }
 
-- (NSData*)value {
+- (id)value {
   return _value.get();
 }