chrome: Cleanup class/struct forward declarations

chrome/browser/search/instant_io_context.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 CHROME_BROWSER_SEARCH_INSTANT_IO_CONTEXT_H_
 #define CHROME_BROWSER_SEARCH_INSTANT_IO_CONTEXT_H_
 
 #include <set>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 
-class GURL;
-
 namespace content {
 class ResourceContext;
 }
 
 namespace net {
 class URLRequest;
 }
 
 // IO thread data held for Instant.  This reflects the data held in
 // InstantService for use on the IO thread.  Owned by ResourceContext
@@ skipping 39 matching lines @@
 
   // The process IDs associated with Instant processes.  Mirror of the process
   // IDs in InstantService.  Duplicated here for synchronous access on the IO
   // thread.
   std::set<int> process_ids_;
 
   DISALLOW_COPY_AND_ASSIGN(InstantIOContext);
 };
 
 #endif  // CHROME_BROWSER_SEARCH_INSTANT_IO_CONTEXT_H_