components: Cleanup class/struct fwd declarations

components/sessions/core/session_types.h

 // Copyright 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.
 
 #ifndef COMPONENTS_SESSIONS_CORE_SESSION_TYPES_H_
 #define COMPONENTS_SESSIONS_CORE_SESSION_TYPES_H_
 
 #include <algorithm>
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/strings/string16.h"
 #include "base/time/time.h"
 #include "components/sessions/core/serialized_navigation_entry.h"
 #include "components/sessions/core/session_id.h"
 #include "components/sessions/core/sessions_export.h"
 #include "components/sync/protocol/session_specifics.pb.h"
 #include "components/variations/variations_associated_data.h"
 #include "ui/base/ui_base_types.h"
 #include "ui/gfx/geometry/rect.h"
 #include "url/gurl.h"
 
-namespace content {
-class BrowserContext;
-class NavigationEntry;
-}
-
 namespace sessions {
 
 // SessionTab ----------------------------------------------------------------
 
 // SessionTab corresponds to a NavigationController.
 struct SESSIONS_EXPORT SessionTab {
   SessionTab();
   ~SessionTab();
 
   // Since the current_navigation_index can be larger than the index for number
@@ skipping 133 matching lines @@
 
   std::string app_name;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SessionWindow);
 };
 
 }  // namespace sessions
 
 #endif  // COMPONENTS_SESSIONS_CORE_SESSION_TYPES_H_