Cleanup remaining class/struct fwd declarations

ui/views/mus/pointer_watcher_event_router2.h

 // Copyright 2016 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 UI_VIEWS_MUS_POINTER_WATCHER_EVENT_ROUTER2_H_
 #define UI_VIEWS_MUS_POINTER_WATCHER_EVENT_ROUTER2_H_
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/observer_list.h"
 #include "ui/aura/client/capture_client_observer.h"
 #include "ui/aura/mus/window_tree_client_observer.h"
 #include "ui/views/mus/mus_export.h"
 
 namespace aura {
 class WindowTreeClient;
-namespace client {
-class CaptureClient;
-}
 }
 
 namespace ui {
 class PointerEvent;
 }
 
 namespace views {
 
 class PointerWatcher;
 class PointerWatcherEventRouter2Test;
@@ skipping 52 matching lines @@
   base::ObserverList<views::PointerWatcher, true> move_watchers_;
 
   EventTypes event_types_ = EventTypes::NONE;
 
   DISALLOW_COPY_AND_ASSIGN(PointerWatcherEventRouter2);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_MUS_POINTER_WATCHER_EVENT_ROUTER2_H_