Add more out of line copy ctors for complex classes.

components/mus/ws/platform_display_init_params.h

 // Copyright 2016 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 COMPONENTS_MUS_WS_PLATFORM_DISPLAY_INIT_PARAMS_H_
 #define COMPONENTS_MUS_WS_PLATFORM_DISPLAY_INIT_PARAMS_H_
 
 #include "base/memory/ref_counted.h"
 
 namespace mojo {
 class Connector;
 }
 
 namespace mus {
 
 class GpuState;
 class SurfacesState;
 
 namespace ws {
 
 struct PlatformDisplayInitParams {
   PlatformDisplayInitParams();
+  PlatformDisplayInitParams(const PlatformDisplayInitParams& other);
   ~PlatformDisplayInitParams();
 
   mojo::Connector* connector = nullptr;
   scoped_refptr<GpuState> gpu_state;
   scoped_refptr<SurfacesState> surfaces_state;
 };
 
 }  // namespace ws
 }  // namespace mus
 
 #endif  // COMPONENTS_MUS_WS_PLATFORM_DISPLAY_INIT_PARAMS_H_