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

ui/shell_dialogs/select_file_dialog_mac.mm

 // Copyright (c) 2012 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 "ui/shell_dialogs/select_file_dialog_mac.h"
 
 #include <CoreServices/CoreServices.h>
 #include <stddef.h>
 
 #include <vector>
@@ skipping 230 matching lines @@
                          type:type
                  parentWindow:owning_window];
   }];
 }
 
 SelectFileDialogImpl::DialogData::DialogData(
     void* params_,
     base::scoped_nsobject<ExtensionDropdownHandler> handler)
     : params(params_), extension_dropdown_handler(handler) {}
 
+SelectFileDialogImpl::DialogData::DialogData(const DialogData& other) = default;
+
 SelectFileDialogImpl::DialogData::~DialogData() {}
 
 SelectFileDialogImpl::~SelectFileDialogImpl() {
   // Walk through the open dialogs and close them all.  Use a temporary vector
   // to hold the pointers, since we can't delete from the map as we're iterating
   // through it.
   std::vector<NSSavePanel*> panels;
   for (const auto& value : dialog_data_map_)
     panels.push_back(value.first);
 
@@ skipping 179 matching lines @@
     // For save dialogs, this causes the first item in the allowedFileTypes
     // array to be used as the extension for the save panel.
     [dialog_ setAllowedFileTypes:[fileTypeLists_ objectAtIndex:index]];
   } else {
     // The user selected "All files" option.
     [dialog_ setAllowedFileTypes:nil];
   }
 }
 
 @end