net: Cleanup class/struct forward declarations

net/cert/internal/trust_store_in_memory.h

 // Copyright 2016 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 NET_CERT_INTERNAL_TRUST_STORE_IN_MEMORY_H_
 #define NET_CERT_INTERNAL_TRUST_STORE_IN_MEMORY_H_
 
 #include <unordered_map>
 
 #include "base/memory/ref_counted.h"
 #include "base/strings/string_piece.h"
 #include "net/base/net_export.h"
 #include "net/cert/internal/trust_store.h"
 
 namespace net {
 
-namespace der {
-class Input;
-}
-
 // A very simple implementation of a TrustStore, which contains a set of
 // trust anchors.
 class NET_EXPORT TrustStoreInMemory : public TrustStore {
  public:
   TrustStoreInMemory();
   ~TrustStoreInMemory() override;
 
   // Empties the trust store, resetting it to original state.
   void Clear();
 
   void AddTrustAnchor(scoped_refptr<TrustAnchor> anchor);
 
   // TrustStore implementation:
   void FindTrustAnchorsForCert(const scoped_refptr<ParsedCertificate>& cert,
                                TrustAnchors* matches) const override;
 
  private:
   // Multimap from normalized subject -> TrustAnchor.
   std::unordered_multimap<base::StringPiece,
                           scoped_refptr<TrustAnchor>,
                           base::StringPieceHash>
       anchors_;
 
   DISALLOW_COPY_AND_ASSIGN(TrustStoreInMemory);
 };
 
 }  // namespace net
 
 #endif  // NET_CERT_INTERNAL_TRUST_STORE_IN_MEMORY_H_