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

components/favicon/core/favicon_url.cc

 // Copyright 2014 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/favicon/core/favicon_url.h"
 
 namespace favicon {
 
 FaviconURL::FaviconURL() : icon_type(favicon_base::INVALID_ICON) {
 }
 
 FaviconURL::FaviconURL(const GURL& url,
                        favicon_base::IconType type,
                        const std::vector<gfx::Size>& sizes)
     : icon_url(url), icon_type(type), icon_sizes(sizes) {
 }
 
+FaviconURL::FaviconURL(const FaviconURL& other) = default;
+
 FaviconURL::~FaviconURL() {
 }
 
 }  // namespace favicon