content: Cleanup class/struct forward declarations

content/browser/loader/async_revalidation_driver.h

 // Copyright 2015 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_REVALIDATION_DRIVER_H_
 #define CONTENT_BROWSER_LOADER_ASYNC_REVALIDATION_DRIVER_H_
 
 #include <memory>
 #include <string>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/timer/timer.h"
 #include "content/common/content_export.h"
 #include "content/public/browser/resource_controller.h"
 #include "content/public/browser/resource_throttle.h"
 #include "net/base/io_buffer.h"
 #include "net/url_request/url_request.h"
 
-namespace net {
-class HttpCache;
-}
-
 namespace content {
 
 // This class is responsible for driving the URLRequest for an async
 // revalidation. It is passed an instance of ResourceThrottle created by
 // content::ResourceScheduler to perform throttling on the request.
 class CONTENT_EXPORT AsyncRevalidationDriver : public net::URLRequest::Delegate,
                                                public ResourceController {
  public:
   // |completion_callback| is guaranteed to be called on completion,
   // regardless of success or failure.
@@ skipping 58 matching lines @@
   base::Closure completion_callback_;
 
   base::WeakPtrFactory<AsyncRevalidationDriver> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(AsyncRevalidationDriver);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_LOADER_ASYNC_REVALIDATION_DRIVER_H_