components: Cleanup class/struct fwd declarations

components/sync_sessions/revisit/sessions_page_revisit_observer.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_SYNC_SESSIONS_REVISIT_SESSIONS_PAGE_REVISIT_OBSERVER_H_
 #define COMPONENTS_SYNC_SESSIONS_REVISIT_SESSIONS_PAGE_REVISIT_OBSERVER_H_
 
 #include <memory>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "components/sync_sessions/revisit/page_visit_observer.h"
 
 class GURL;
 
-namespace sessions {
-struct SessionTab;
-}  // namespace sessions
-
 namespace sync_sessions {
 
-class CurrentTabMatcher;
-class OffsetTabMatcher;
 struct SyncedSession;
 
 // A simple interface to abstract away who is providing sessions.
 class ForeignSessionsProvider {
  public:
   // Fills the already instantiated passed vector with all foreign sessions.
   // Returned boolean representes if there were foreign sessions and the vector
   // should be examimed.
   virtual bool GetAllForeignSessions(
       std::vector<const SyncedSession*>* sessions) = 0;
@@ skipping 22 matching lines @@
   void CheckForRevisit(const GURL& url, const TransitionType transition);
 
   std::unique_ptr<ForeignSessionsProvider> provider_;
 
   DISALLOW_COPY_AND_ASSIGN(SessionsPageRevisitObserver);
 };
 
 }  // namespace sync_sessions
 
 #endif  // COMPONENTS_SYNC_SESSIONS_REVISIT_SESSIONS_PAGE_REVISIT_OBSERVER_H_