chrome: Cleanup class/struct forward declarations

chrome/browser/ui/cocoa/extensions/extension_install_dialog_controller.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_COCOA_EXTENSIONS_EXTENSION_INSTALL_DIALOG_CONTROLER_H_
 #define CHROME_BROWSER_UI_COCOA_EXTENSIONS_EXTENSION_INSTALL_DIALOG_CONTROLER_H_
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/mac/scoped_nsobject.h"
 #include "base/macros.h"
 #include "chrome/browser/extensions/extension_install_prompt.h"
 #import "chrome/browser/ui/cocoa/constrained_window/constrained_window_mac.h"
 #import "chrome/browser/ui/cocoa/extensions/extension_install_view_controller.h"
 
-namespace content {
-class PageNavigator;
-class WebContents;
-}
-
 namespace extensions {
 class ExperienceSamplingEvent;
 }
 
 class ExtensionInstallPromptShowParams;
 @class ExtensionInstallViewController;
 
 // Displays an extension install prompt as a tab modal dialog.
 class ExtensionInstallDialogController :
     public ExtensionInstallViewDelegate,
@@ skipping 26 matching lines @@
 
   ExtensionInstallPrompt::DoneCallback done_callback_;
   base::scoped_nsobject<ExtensionInstallViewController> view_controller_;
   std::unique_ptr<ConstrainedWindowMac> constrained_window_;
   std::unique_ptr<extensions::ExperienceSamplingEvent> sampling_event_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionInstallDialogController);
 };
 
 #endif  // CHROME_BROWSER_UI_COCOA_EXTENSIONS_EXTENSION_INSTALL_DIALOG_CONTROLLER_H_