components: Cleanup class/struct fwd declarations

components/update_client/update_client.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_UPDATE_CLIENT_UPDATE_CLIENT_H_
 #define COMPONENTS_UPDATE_CLIENT_UPDATE_CLIENT_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 112 matching lines @@
 // implemented as a mixin. The polymorphic behavior of some of the actions
 // is achieved using a template method.
 //
 // State changes of a CRX could generate events, which are observed using a
 // subject-observer interface.
 //
 // The actions chain up. In some sense, the actions implement a state machine,
 // as the CRX undergoes a series of state transitions in the process of
 // being checked for updates and applying the update.
 
-class ComponentsUI;
 class PrefRegistrySimple;
 
 namespace base {
 class DictionaryValue;
 class FilePath;
 }
 
 namespace update_client {
 
 class Configurator;
@@ skipping 212 matching lines @@
 scoped_refptr<UpdateClient> UpdateClientFactory(
     const scoped_refptr<Configurator>& config);
 
 // This must be called prior to the construction of any Configurator that
 // contains a PrefService.
 void RegisterPrefs(PrefRegistrySimple* registry);
 
 }  // namespace update_client
 
 #endif  // COMPONENTS_UPDATE_CLIENT_UPDATE_CLIENT_H_