Remove base::NonThreadSafe now that all users are gone!!

remoting/host/it2me/it2me_confirmation_dialog_proxy.h

 // 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.
 
 #ifndef REMOTING_HOST_IT2ME_IT2ME_CONFIRMATION_DIALOG_PROXY_H_
 #define REMOTING_HOST_IT2ME_IT2ME_CONFIRMATION_DIALOG_PROXY_H_
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/single_thread_task_runner.h"
-#include "base/threading/non_thread_safe.h"
 #include "remoting/host/it2me/it2me_confirmation_dialog.h"
 
 namespace remoting {
 
 // A helper class to use an It2MeConfirmationDialog from a non-UI thread.
 class It2MeConfirmationDialogProxy : public It2MeConfirmationDialog {
  public:
   // |ui_task_runner| must be the UI thread. It will be used to call into the
   // wrapped dialog.
   // |dialog| is the dialog being wrapped.
@@ skipping 15 matching lines @@
   std::unique_ptr<Core> core_;
   It2MeConfirmationDialog::ResultCallback callback_;
   base::WeakPtrFactory<It2MeConfirmationDialogProxy> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(It2MeConfirmationDialogProxy);
 };
 
 }  // namespace remoting
 
 #endif  // REMOTING_HOST_IT2ME_IT2ME_CONFIRMATION_DIALOG_PROXY_H_