chrome: Cleanup class/struct forward declarations

chrome/browser/extensions/api/downloads/downloads_api.h

 // 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.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_API_DOWNLOADS_DOWNLOADS_API_H_
 #define CHROME_BROWSER_EXTENSIONS_API_DOWNLOADS_DOWNLOADS_API_H_
 
 #include <memory>
 #include <set>
 #include <string>
 
 #include "base/files/file_path.h"
 #include "base/macros.h"
 #include "base/scoped_observer.h"
 #include "base/time/time.h"
 #include "chrome/browser/download/all_download_item_notifier.h"
 #include "chrome/browser/download/download_danger_prompt.h"
 #include "chrome/browser/download/download_path_reservation_tracker.h"
 #include "chrome/browser/extensions/chrome_extension_function.h"
 #include "chrome/common/extensions/api/downloads.h"
 #include "content/public/browser/download_manager.h"
 #include "extensions/browser/event_router.h"
 #include "extensions/browser/extension_registry_observer.h"
 #include "extensions/browser/warning_set.h"
 
 class DownloadFileIconExtractor;
-class DownloadQuery;
-
-namespace content {
-class ResourceContext;
-class ResourceDispatcherHost;
-}
 
 namespace extensions {
 class ExtensionRegistry;
 }
 
 // Functions in the chrome.downloads namespace facilitate
 // controlling downloads from extensions. See the full API doc at
 // http://goo.gl/6hO1n
 
 namespace download_extension_errors {
@@ skipping 364 matching lines @@
   ScopedObserver<extensions::ExtensionRegistry,
                  extensions::ExtensionRegistryObserver>
       extension_registry_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionDownloadsEventRouter);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_DOWNLOADS_DOWNLOADS_API_H_