components: Add out-of-line copy ctors for complex classes.

components/proximity_auth/remote_device.cc

 // 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 "components/proximity_auth/remote_device.h"
 
 namespace proximity_auth {
 
 RemoteDevice::RemoteDevice() : bluetooth_type(BLUETOOTH_CLASSIC) {}
 
 RemoteDevice::RemoteDevice(const std::string& user_id,
                            const std::string& name,
                            const std::string& public_key,
                            BluetoothType bluetooth_type,
                            const std::string& bluetooth_address,
                            const std::string& persistent_symmetric_key,
                            std::string sign_in_challenge)
     : user_id(user_id),
       name(name),
       public_key(public_key),
       bluetooth_type(bluetooth_type),
       bluetooth_address(bluetooth_address),
       persistent_symmetric_key(persistent_symmetric_key),
       sign_in_challenge(sign_in_challenge) {}
 
+RemoteDevice::RemoteDevice(const RemoteDevice& other) = default;
+
 RemoteDevice::~RemoteDevice() {}
 
 }  // namespace