Nukes view_manager namespace

mojo/services/public/cpp/view_manager/lib/node_observer.cc

 // 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.
 
 #include "mojo/services/public/cpp/view_manager/node_observer.h"
 
 #include "base/basictypes.h"
 
 namespace mojo {
-namespace view_manager {
 
 ////////////////////////////////////////////////////////////////////////////////
 // NodeObserver, public:
 
 NodeObserver::TreeChangeParams::TreeChangeParams()
     : target(NULL),
       old_parent(NULL),
       new_parent(NULL),
       receiver(NULL) {}
 
-}  // namespace view_manager
 }  // namespace mojo