components: Cleanup class/struct fwd declarations

components/error_page/renderer/net_error_helper_core.h

 // Copyright 2013 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 COMPONENTS_ERROR_PAGE_RENDERER_NET_ERROR_HELPER_CORE_H_
 #define COMPONENTS_ERROR_PAGE_RENDERER_NET_ERROR_HELPER_CORE_H_
 
 #include <memory>
 #include <string>
 
 #include "base/callback.h"
 #include "base/memory/weak_ptr.h"
 #include "base/timer/timer.h"
 #include "build/build_config.h"
 #include "components/error_page/common/net_error_info.h"
 #include "url/gurl.h"
 
-namespace base {
-class ListValue;
-}
-
 namespace blink {
 struct WebURLError;
 }
 
 namespace error_page {
 
 struct ErrorPageParams;
 
 // Class that contains the logic for how the NetErrorHelper.  This allows for
 // testing the logic without a RenderView or WebFrame, which are difficult to
@@ skipping 253 matching lines @@
 
   // This value is set only when a navigation has been initiated from
   // the error page.  It is used to detect when such navigations result
   // in errors.
   Button navigation_from_button_;
 };
 
 }  // namespace error_page
 
 #endif  // COMPONENTS_ERROR_PAGE_RENDERER_NET_ERROR_HELPER_CORE_H_