content: Cleanup class/struct forward declarations

content/browser/loader/async_resource_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 CONTENT_BROWSER_LOADER_ASYNC_RESOURCE_HANDLER_H_
 #define CONTENT_BROWSER_LOADER_ASYNC_RESOURCE_HANDLER_H_
 
 #include <stdint.h>
 
 #include <string>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/timer/timer.h"
 #include "content/browser/loader/resource_handler.h"
 #include "content/browser/loader/resource_message_delegate.h"
 #include "content/common/content_export.h"
 #include "net/base/io_buffer.h"
 #include "url/gurl.h"
 
 namespace net {
 class URLRequest;
 }
 
 namespace content {
 class ResourceBuffer;
-class ResourceContext;
 class ResourceDispatcherHostImpl;
-class ResourceMessageFilter;
-class SharedIOBuffer;
 
 // Used to complete an asynchronous resource request in response to resource
 // load events from the resource dispatcher host.
 class CONTENT_EXPORT AsyncResourceHandler : public ResourceHandler,
                                             public ResourceMessageDelegate {
  public:
   AsyncResourceHandler(net::URLRequest* request,
                        ResourceDispatcherHostImpl* rdh);
   ~AsyncResourceHandler() override;
 
@@ skipping 58 matching lines @@
 
   int64_t reported_transfer_size_;
   int64_t reported_encoded_body_length_;
 
   DISALLOW_COPY_AND_ASSIGN(AsyncResourceHandler);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_LOADER_ASYNC_RESOURCE_HANDLER_H_