Adding std::ostream& operator<<(std::ostream& out, NSError* error)

device/bluetooth/bluetooth_adapter_mac.h

 // 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.
 
 #ifndef DEVICE_BLUETOOTH_BLUETOOTH_ADAPTER_MAC_H_
 #define DEVICE_BLUETOOTH_BLUETOOTH_ADAPTER_MAC_H_
 
 #include <IOKit/IOReturn.h>
 
 #include <memory>
@@ skipping 211 matching lines @@
   base::scoped_nsobject<BluetoothLowEnergyCentralManagerDelegate>
       low_energy_central_manager_delegate_;
 
   scoped_refptr<base::SequencedTaskRunner> ui_task_runner_;
 
   base::WeakPtrFactory<BluetoothAdapterMac> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(BluetoothAdapterMac);
 };
 
+// Stream operator for logging.
+DEVICE_BLUETOOTH_EXPORT std::ostream& operator<<(std::ostream& out,
+                                                 NSError* error);
+
 }  // namespace device
 
 #endif  // DEVICE_BLUETOOTH_BLUETOOTH_ADAPTER_MAC_H_