Make UiElement a class

chrome/browser/android/vr_shell/ui_scene_manager.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 CHROME_BROWSER_ANDROID_VR_SHELL_UI_SCENE_MANAGER_H_
 #define CHROME_BROWSER_ANDROID_VR_SHELL_UI_SCENE_MANAGER_H_
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/timer/timer.h"
 #include "base/values.h"
 
 namespace vr_shell {
 
-struct UiElement;
+class UiElement;
 class UiScene;
 class VrBrowserInterface;
 
 class UiSceneManager {
  public:
   UiSceneManager(VrBrowserInterface* browser, UiScene* scene);
   ~UiSceneManager();
 
   base::WeakPtr<UiSceneManager> GetWeakPtr();
 
@@ skipping 30 matching lines @@
   base::OneShotTimer security_warning_timer_;
 
   base::WeakPtrFactory<UiSceneManager> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(UiSceneManager);
 };
 
 }  // namespace vr_shell
 
 #endif  // CHROME_BROWSER_ANDROID_VR_SHELL_UI_SCENE_MANAGER_H_