Bluetooth: macOS: Making code to get mac descriptors more coherent

device/bluetooth/bluetooth_low_energy_device_mac.mm

 // Copyright 2015 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_low_energy_device_mac.h"
 
 #import <CoreFoundation/CoreFoundation.h>
 #include <stddef.h>
 
 #include "base/mac/mac_util.h"
@@ skipping 472 matching lines @@
   if (!gatt_service_mac) {
     return nullptr;
   }
   return gatt_service_mac->GetBluetoothRemoteGattCharacteristicMac(
       cb_characteristic);
 }
 
 BluetoothRemoteGattDescriptorMac*
 BluetoothLowEnergyDeviceMac::GetBluetoothRemoteGattDescriptorMac(
     CBDescriptor* cb_descriptor) const {
-  CBCharacteristic* cb_characteristic = cb_descriptor.characteristic;
-  BluetoothRemoteGattServiceMac* gatt_service =
-      GetBluetoothRemoteGattServiceMac(cb_characteristic.service);
-  DCHECK(gatt_service);
-  BluetoothRemoteGattCharacteristicMac* gatt_characteristic =
-      gatt_service->GetBluetoothRemoteGattCharacteristicMac(cb_characteristic);
-  DCHECK(gatt_characteristic);
-  return gatt_characteristic->GetBluetoothRemoteGattDescriptorMac(
-      cb_descriptor);
+  CBService* cb_service = [[cb_descriptor characteristic] service];
+  BluetoothRemoteGattServiceMac* gatt_service_mac =
+      GetBluetoothRemoteGattServiceMac(cb_service);
+  if (!gatt_service_mac) {
+    return nullptr;
+  }
+  return gatt_service_mac->GetBluetoothRemoteGattDescriptorMac(cb_descriptor);
 }
 
 void BluetoothLowEnergyDeviceMac::DidDisconnectPeripheral(NSError* error) {
   connected_ = false;
   VLOG(1) << *this << ": Disconnected from peripheral.";
   if (error) {
     VLOG(1) << *this
             << ": Bluetooth error: " << BluetoothAdapterMac::String(error);
   }
   SetGattServicesDiscoveryComplete(false);
@@ skipping 23 matching lines @@
   // BluetoothLowEnergyDeviceMac::GetNameForDisplay() instead.
   base::Optional<std::string> name = device.GetName();
   const char* is_gatt_connected =
       device.IsGattConnected() ? "GATT connected" : "GATT disconnected";
   return out << "<BluetoothLowEnergyDeviceMac " << device.GetAddress() << "/"
              << &device << ", " << is_gatt_connected << ", \""
              << name.value_or("Unnamed device") << "\">";
 }
 
 }  // namespace device