components: Cleanup class/struct fwd declarations

components/invalidation/impl/invalidation_state_tracker.h

 // Copyright 2014 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.
 //
 // An InvalidationStateTracker is an interface that handles persisting state
 // needed for invalidations. Currently, it is responsible for managing the
 // following information:
 // - Max version seen from the invalidation server to help dedupe invalidations.
 // - Bootstrap data for the invalidation client.
 // - Payloads and locally generated ack handles, to support local acking.
 
 #ifndef COMPONENTS_INVALIDATION_IMPL_INVALIDATION_STATE_TRACKER_H_
 #define COMPONENTS_INVALIDATION_IMPL_INVALIDATION_STATE_TRACKER_H_
 
 #include <map>
 #include <string>
 
 #include "base/callback_forward.h"
 #include "base/memory/ref_counted.h"
 #include "components/invalidation/impl/unacked_invalidation_set.h"
 #include "components/invalidation/public/invalidation.h"
 #include "components/invalidation/public/invalidation_export.h"
 #include "components/invalidation/public/invalidation_util.h"
 #include "google/cacheinvalidation/include/types.h"
 
-namespace base {
-class TaskRunner;
-}  // namespace base
-
 namespace syncer {
 
 class INVALIDATION_EXPORT InvalidationStateTracker {
  public:
   InvalidationStateTracker();
   virtual ~InvalidationStateTracker();
 
   // The per-client unique ID used to register the invalidation client with the
   // server.  This is used to squelch invalidation notifications that originate
   // from changes made by this client.  Setting the client ID clears all other
@@ skipping 14 matching lines @@
   virtual void SetSavedInvalidations(const UnackedInvalidationsMap& states) = 0;
   virtual UnackedInvalidationsMap GetSavedInvalidations() const = 0;
 
   // Erases invalidation versions, client ID, and state stored on disk.
   virtual void Clear() = 0;
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_INVALIDATION_IMPL_INVALIDATION_STATE_TRACKER_H_