chrome: Cleanup class/struct forward declarations

chrome/browser/ui/webui/print_preview/print_preview_handler.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_UI_WEBUI_PRINT_PREVIEW_PRINT_PREVIEW_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_PRINT_PREVIEW_PRINT_PREVIEW_HANDLER_H_
 
 #include <memory>
 #include <string>
 
 #include "base/files/file_path.h"
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "chrome/common/features.h"
 #include "components/signin/core/browser/gaia_cookie_manager_service.h"
 #include "content/public/browser/web_ui_message_handler.h"
 #include "printing/backend/print_backend.h"
 #include "printing/features/features.h"
 #include "ui/shell_dialogs/select_file_dialog.h"
 
 #if BUILDFLAG(ENABLE_SERVICE_DISCOVERY)
 #include "chrome/browser/local_discovery/service_discovery_shared_client.h"
 #include "chrome/browser/printing/cloud_print/privet_local_printer_lister.h"
 #endif
 
 class PrinterHandler;
 class PrintPreviewUI;
-class PrintSystemTaskProxy;
 
 namespace base {
 class DictionaryValue;
 class RefCountedBytes;
 }
 
 namespace content {
 class WebContents;
 }
 
@@ skipping 339 matching lines @@
   // Notifies tests that want to know if the PDF has been saved. This doesn't
   // notify the test if it was a successful save, only that it was attempted.
   base::Closure pdf_file_saved_closure_;
 
   base::WeakPtrFactory<PrintPreviewHandler> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PrintPreviewHandler);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_PRINT_PREVIEW_PRINT_PREVIEW_HANDLER_H_