chrome: Cleanup class/struct forward declarations

chrome/browser/plugins/plugin_infobar_delegates.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_PLUGINS_PLUGIN_INFOBAR_DELEGATES_H_
 #define CHROME_BROWSER_PLUGINS_PLUGIN_INFOBAR_DELEGATES_H_
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "build/build_config.h"
 #include "chrome/common/features.h"
 #include "components/infobars/core/confirm_infobar_delegate.h"
 #include "url/gurl.h"
 
 #if BUILDFLAG(ENABLE_PLUGIN_INSTALLATION)
 #include "chrome/browser/plugins/plugin_installer_observer.h"
 #endif
 
 class InfoBarService;
-class HostContentSettingsMap;
 class PluginMetadata;
 
-namespace content {
-class WebContents;
-}
-
 #if BUILDFLAG(ENABLE_PLUGIN_INSTALLATION)
 // Infobar that's shown when a plugin is out of date.
 class OutdatedPluginInfoBarDelegate : public ConfirmInfoBarDelegate,
                                       public WeakPluginInstallerObserver {
  public:
   // Creates an outdated plugin infobar and delegate and adds the infobar to
   // |infobar_service|.
   static void Create(InfoBarService* infobar_service,
                      PluginInstaller* installer,
                      std::unique_ptr<PluginMetadata> metadata);
@@ skipping 39 matching lines @@
 
   std::unique_ptr<PluginMetadata> plugin_metadata_;
 
   base::string16 message_;
 
   DISALLOW_COPY_AND_ASSIGN(OutdatedPluginInfoBarDelegate);
 };
 #endif  // BUILDFLAG(ENABLE_PLUGIN_INSTALLATION)
 
 #endif  // CHROME_BROWSER_PLUGINS_PLUGIN_INFOBAR_DELEGATES_H_