Consolidate javascript_dialog_manager.h and javascript_dialog_manager_impl.h

components/app_modal/native_app_modal_dialog.h

 // Copyright (c) 2011 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_APP_MODAL_NATIVE_APP_MODAL_DIALOG_H_
 #define COMPONENTS_APP_MODAL_NATIVE_APP_MODAL_DIALOG_H_
 
 #include "ui/gfx/native_widget_types.h"
 
+namespace app_modal {
+
 class JavaScriptAppModalDialog;
 
 class NativeAppModalDialog {
  public:
   // Returns the buttons to be shown. See ui::DialogButton for which buttons can
   // be returned.
   virtual int GetAppModalDialogButtons() const = 0;
 
   // Shows the dialog.
   virtual void ShowAppModalDialog() = 0;
 
   // Activates the dialog.
   virtual void ActivateAppModalDialog() = 0;
 
   // Closes the dialog.
   virtual void CloseAppModalDialog() = 0;
 
   // Accepts or cancels the dialog.
   virtual void AcceptAppModalDialog() = 0;
   virtual void CancelAppModalDialog() = 0;
 };
 
+}  // namespace app_modal
+
 #endif  // COMPONENTS_APP_MODAL_NATIVE_APP_MODAL_DIALOG_H_