bluetooth: macOS: Adding log in BluetoothAdapterMac::DisconnectGatt()

device/bluetooth/bluetooth_adapter_mac.mm

 // Copyright 2013 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/bluetooth_adapter_mac.h"
 
 #import <IOBluetooth/objc/IOBluetoothDevice.h>
 #import <IOBluetooth/objc/IOBluetoothHostController.h>
 #include <stddef.h>
 
@@ skipping 623 matching lines @@
       }
     }
     connected_devices.push_back(device_mac);
     VLOG(1) << *device_mac << ": New connected device.";
   }
   return connected_devices;
 }
 
 void BluetoothAdapterMac::CreateGattConnection(
     BluetoothLowEnergyDeviceMac* device_mac) {
+  DCHECK(device_mac);

[scheib, 2017/03/30 22:48:41]

This DCHECK is redundant with the "*device_mac" isn't it? If device_mac is null
then a crash will occur and the stack should be produced blaming that line, it
should be easy to understand. -- If I'm wrong, by all means use a DCHECK to make
it clear.

[jlebel, 2017/03/30 23:16:08]

It will crash, but somewhere in operator<< related to
BluetoothLowEnergyDeviceMac. My idea was to make it very clear. There is also
one difference, null will be caught by the DCHECK, a deallocated device will
crash in the operator<<.

Do you think I should remove the DCHECK?

[jlebel, 2017/03/31 07:39:12]

Done.

+  VLOG(1) << *device_mac << ": Create gatt connection.";
   [low_energy_central_manager_ connectPeripheral:device_mac->peripheral_
                                          options:nil];
 }
 
 void BluetoothAdapterMac::DisconnectGatt(
     BluetoothLowEnergyDeviceMac* device_mac) {
+  DCHECK(device_mac);
+  VLOG(1) << *device_mac << ": Disconnect gatt.";
   [low_energy_central_manager_
       cancelPeripheralConnection:device_mac->peripheral_];
 }
 
 void BluetoothAdapterMac::DidConnectPeripheral(CBPeripheral* peripheral) {
   BluetoothLowEnergyDeviceMac* device_mac =
       GetBluetoothLowEnergyDeviceMac(peripheral);
   if (!device_mac) {
     [low_energy_central_manager_ cancelPeripheralConnection:peripheral];
     return;
@@ skipping 60 matching lines @@
     // hash the probability of this occuring with 10,000 devices
     // simultaneously present is 1e-6 (see
     // https://en.wikipedia.org/wiki/Birthday_problem#Probability_table).  We
     // ignore the second device by returning.
     return true;
   }
   return false;
 }
 
 }  // namespace device