bluetooth: macOS: Adding explicit function to log NSError

device/bluetooth/bluetooth_adapter_mac.h

Index: device/bluetooth/bluetooth_adapter_mac.h
diff --git a/device/bluetooth/bluetooth_adapter_mac.h b/device/bluetooth/bluetooth_adapter_mac.h
index 543d1953d8cc19b7dc20e7f703b92a6fd4888590..fb832c862bd3adf69d9cc4647ff9285f4e226ca5 100644
--- a/device/bluetooth/bluetooth_adapter_mac.h
+++ b/device/bluetooth/bluetooth_adapter_mac.h
@@ -53,6 +53,9 @@ class DEVICE_BLUETOOTH_EXPORT BluetoothAdapterMac
   // Converts CBUUID into BluetoothUUID
   static BluetoothUUID BluetoothUUIDWithCBUUID(CBUUID* UUID);
 
+  // Converts NSError to string for logging.
+  static std::string String(NSError* error);
+
   // BluetoothAdapter overrides:
   std::string GetAddress() const override;
   std::string GetName() const override;
@@ -229,10 +232,6 @@ class DEVICE_BLUETOOTH_EXPORT BluetoothAdapterMac
   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_