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

chrome/common/extensions/api/notifications/notification_style.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 "chrome/common/extensions/api/notifications/notification_style.h"
 
 #include "ui/message_center/message_center_style.h"
 
 NotificationBitmapSizes::NotificationBitmapSizes() {
 }
+NotificationBitmapSizes::NotificationBitmapSizes(
+    const NotificationBitmapSizes& other) = default;
 NotificationBitmapSizes::~NotificationBitmapSizes() {
 }
 
 NotificationBitmapSizes GetNotificationBitmapSizes() {
   NotificationBitmapSizes sizes;
   sizes.image_size =
       gfx::Size(message_center::kNotificationPreferredImageWidth,
                 message_center::kNotificationPreferredImageHeight);
   sizes.icon_size = gfx::Size(message_center::kNotificationIconSize,
                               message_center::kNotificationIconSize);
   sizes.button_icon_size =
       gfx::Size(message_center::kNotificationButtonIconSize,
                 message_center::kNotificationButtonIconSize);
 
   sizes.app_icon_mask_size = gfx::Size(message_center::kSmallImageSize,
                                        message_center::kSmallImageSize);
   return sizes;
 }