components: Cleanup class/struct fwd declarations

components/certificate_transparency/log_proof_fetcher.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 COMPONENTS_CERTIFICATE_TRANSPARENCY_LOG_PROOF_FETCHER_H_
 #define COMPONENTS_CERTIFICATE_TRANSPARENCY_LOG_PROOF_FETCHER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 
-namespace base {
-class Value;
-}  // namespace base
-
 namespace net {
 
 class URLRequestContext;
 
 namespace ct {
 struct SignedTreeHead;
 }  // namespace ct
 
 }  // namespace net
 
@@ skipping 91 matching lines @@
   std::set<std::unique_ptr<LogResponseHandler>> inflight_fetches_;
 
   base::WeakPtrFactory<LogProofFetcher> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(LogProofFetcher);
 };
 
 }  // namespace certificate_transparency
 
 #endif  // COMPONENTS_CERTIFICATE_TRANSPARENCY_LOG_PROOF_FETCHER_H_