Bluetooth: macOS: Adding counter for service discovery callbacks.

device/bluetooth/test/mock_bluetooth_cbperipheral_mac.mm

Index: device/bluetooth/test/mock_bluetooth_cbperipheral_mac.mm
diff --git a/device/bluetooth/test/mock_bluetooth_cbperipheral_mac.mm b/device/bluetooth/test/mock_bluetooth_cbperipheral_mac.mm
index a11a11ba5ddcda7c04fd1e30664aa8673f009963..75a1de62ee7abc1e578067256d47a66eb900b08c 100644
--- a/device/bluetooth/test/mock_bluetooth_cbperipheral_mac.mm
+++ b/device/bluetooth/test/mock_bluetooth_cbperipheral_mac.mm
@@ -83,11 +83,13 @@ using base::scoped_nsobject;
   if (_bluetoothTestMac) {
     _bluetoothTestMac->OnFakeBluetoothServiceDiscovery();
   }
-  [_delegate peripheral:self.peripheral didDiscoverServices:nil];
 }
 
 - (void)discoverCharacteristics:(NSArray*)characteristics
                      forService:(CBService*)service {
+  if (_bluetoothTestMac) {
+    _bluetoothTestMac->OnFakeBluetoothCharacteristicDiscovery();
+  }
 }
 
 - (void)discoverDescriptorsForCharacteristic:(CBCharacteristic*)characteristic {