Bluetooth: macOS: Implementing read/write for descriptors

device/bluetooth/test/mock_bluetooth_cbdescriptor_mac.mm

Index: device/bluetooth/test/mock_bluetooth_cbdescriptor_mac.mm
diff --git a/device/bluetooth/test/mock_bluetooth_cbdescriptor_mac.mm b/device/bluetooth/test/mock_bluetooth_cbdescriptor_mac.mm
index 9c8512b5142a99d2d765d2fdbfd5099525492e0e..3a2f6152cc760c43c3c70542fa6d4aa04a1216fe 100644
--- a/device/bluetooth/test/mock_bluetooth_cbdescriptor_mac.mm
+++ b/device/bluetooth/test/mock_bluetooth_cbdescriptor_mac.mm
@@ -15,6 +15,7 @@ using base::scoped_nsobject;
   // Owner of this instance.
   CBCharacteristic* _characteristic;
   scoped_nsobject<CBUUID> _UUID;
+  scoped_nsobject<NSData> _value;
 }
 @end
 
@@ -50,6 +51,10 @@ using base::scoped_nsobject;
   return _UUID.get();
 }
 
+- (NSData*)value {
+  return _value.get();
+}
+
 - (CBDescriptor*)descriptor {
   return ObjCCast<CBDescriptor>(self);
 }
@@ -58,4 +63,19 @@ using base::scoped_nsobject;
   return _characteristic;
 }
 
+- (void)simulateReadWithValue:(id)value error:(NSError*)error {
+  _value.reset([value copy]);
+  CBPeripheral* peripheral = _characteristic.service.peripheral;
+  [peripheral.delegate peripheral:peripheral
+      didUpdateValueForDescriptor:self.descriptor
+                            error:error];
+}
+
+- (void)simulateWriteWithError:(NSError*)error {
+  CBPeripheral* peripheral = _characteristic.service.peripheral;
+  [peripheral.delegate peripheral:peripheral
+       didWriteValueForDescriptor:self.descriptor
+                            error:error];
+}
+
 @end