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

chrome/browser/prefs/session_startup_pref.cc

 // 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 "chrome/browser/prefs/session_startup_pref.h"
 
 #include <stddef.h>
 
 #include <string>
 
@@ skipping 134 matching lines @@
 SessionStartupPref::Type SessionStartupPref::PrefValueToType(int pref_value) {
   switch (pref_value) {
     case kPrefValueLast:     return SessionStartupPref::LAST;
     case kPrefValueURLs:     return SessionStartupPref::URLS;
     default:                 return SessionStartupPref::DEFAULT;
   }
 }
 
 SessionStartupPref::SessionStartupPref(Type type) : type(type) {}
 
+SessionStartupPref::SessionStartupPref(const SessionStartupPref& other) =
+    default;
+
 SessionStartupPref::~SessionStartupPref() {}