chrome: Cleanup class/struct forward declarations

chrome/browser/download/notification/download_item_notification.h

 // Copyright 2015 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 CHROME_BROWSER_DOWNLOAD_NOTIFICATION_DOWNLOAD_ITEM_NOTIFICATION_H_
 #define CHROME_BROWSER_DOWNLOAD_NOTIFICATION_DOWNLOAD_ITEM_NOTIFICATION_H_
 
 #include "base/macros.h"
 #include "base/strings/string_number_conversions.h"
 #include "chrome/browser/download/download_commands.h"
@@ skipping 11 matching lines @@
 class SkBitmap;
 
 namespace test {
 class DownloadItemNotificationTest;
 }
 
 namespace gfx {
 enum class VectorIconId;
 }
 
+class DownloadNotificationManagerForProfile;
+
 class DownloadItemNotification : public DownloadNotification,
                                  public ImageDecoder::ImageRequest {
  public:
   DownloadItemNotification(content::DownloadItem* item,
                            DownloadNotificationManagerForProfile* manager);
 
   ~DownloadItemNotification() override;
 
   // Methods called from NotificationWatcher.
   void OnDownloadUpdated(content::DownloadItem* item) override;
@@ skipping 87 matching lines @@
 
   void SetMessageCenterForTest(
       message_center::MessageCenter* message_center);
 
   base::WeakPtrFactory<DownloadItemNotification> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DownloadItemNotification);
 };
 
 #endif  // CHROME_BROWSER_DOWNLOAD_NOTIFICATION_DOWNLOAD_ITEM_NOTIFICATION_H_