[Ozone-Dri] Decouple the IO helper thread from DriWrapper

ui/ozone/platform/dri/dri_helper_thread.h

+// Copyright 2015 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_OZONE_PLATFORM_DRI_DRI_HELPER_THREAD_H_
+#define UI_OZONE_PLATFORM_DRI_DRI_HELPER_THREAD_H_
+
+#include "base/threading/thread.h"
+
+namespace ui {
+
+class DriHelperThread : public base::Thread {
+ public:
+  DriHelperThread();
+  ~DriHelperThread() override;
+
+  // Call to start the thread. This needs to be called after the GPU entered the
+  // sandbox.
+  void Initialize();
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(DriHelperThread);
+};
+
+}  // namespace ui
+
+#endif  // UI_OZONE_PLATFORM_DRI_DRI_HELPER_THREAD_H_