content: Cleanup class/struct forward declarations

content/child/indexed_db/webidbdatabase_impl.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 CONTENT_CHILD_INDEXED_DB_WEBIDBDATABASE_IMPL_H_
 #define CONTENT_CHILD_INDEXED_DB_WEBIDBDATABASE_IMPL_H_
 
 #include <stdint.h>
 
 #include <set>
 
 #include "base/memory/ref_counted.h"
 #include "third_party/WebKit/public/platform/modules/indexeddb/WebIDBCursor.h"
 #include "third_party/WebKit/public/platform/modules/indexeddb/WebIDBDatabase.h"
 #include "third_party/WebKit/public/platform/modules/indexeddb/WebIDBTypes.h"
 
 namespace blink {
 class WebBlobInfo;
 class WebIDBCallbacks;
-class WebIDBDatabaseCallbacks;
 class WebIDBObserver;
 class WebString;
 }
 
 namespace content {
 class ThreadSafeSender;
 
 class WebIDBDatabaseImpl : public blink::WebIDBDatabase {
  public:
   WebIDBDatabaseImpl(int32_t ipc_database_id,
@@ skipping 94 matching lines @@
 
  private:
   int32_t ipc_database_id_;
   std::set<int32_t> observer_ids_;
   scoped_refptr<ThreadSafeSender> thread_safe_sender_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_CHILD_INDEXED_DB_WEBIDBDATABASE_IMPL_H_