components: Cleanup class/struct fwd declarations

components/safe_browsing_db/database_manager.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.
 //
 // The Safe Browsing service is responsible for downloading anti-phishing and
 // anti-malware tables and checking urls against them.
 
 #ifndef COMPONENTS_SAFE_BROWSING_DB_DATABASE_MANAGER_H_
 #define COMPONENTS_SAFE_BROWSING_DB_DATABASE_MANAGER_H_
 
 #include <set>
 #include <string>
 #include <unordered_set>
 #include <vector>
 
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "components/safe_browsing_db/hit_report.h"
 #include "components/safe_browsing_db/util.h"
 #include "content/public/common/resource_type.h"
 #include "url/gurl.h"
 
 namespace net {
 class URLRequestContextGetter;
 }  // namespace net
 
 namespace safe_browsing {
 
-struct ListIdentifier;
 struct V4ProtocolConfig;
 class V4GetHashProtocolManager;
 
 // Base class to either the locally-managed or a remotely-managed database.
 class SafeBrowsingDatabaseManager
     : public base::RefCountedThreadSafe<SafeBrowsingDatabaseManager> {
  public:
   // Callers requesting a result should derive from this class.
   // The destructor should call db_manager->CancelCheck(client) if a
   // request is still pending.
@@ skipping 226 matching lines @@
   std::unique_ptr<V4GetHashProtocolManager> v4_get_hash_protocol_manager_;
 
  private:
   // Returns an iterator to the pending API check with the given |client|.
   ApiCheckSet::iterator FindClientApiCheck(Client* client);
 };  // class SafeBrowsingDatabaseManager
 
 }  // namespace safe_browsing
 
 #endif  // COMPONENTS_SAFE_BROWSING_DB_DATABASE_MANAGER_H_