Make ozone/drm/mojo more immune to startup races

ui/ozone/platform/drm/cursor_proxy_mojo.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 UI_OZONE_PLATFORM_DRM_CURSOR_PROXY_MOJO_H_
 #define UI_OZONE_PLATFORM_DRM_CURSOR_PROXY_MOJO_H_
 
 #include "ui/gfx/native_widget_types.h"
 #include "ui/ozone/platform/drm/gpu/inter_thread_messaging_proxy.h"
 #include "ui/ozone/platform/drm/host/drm_cursor.h"
@@ skipping 15 matching lines @@
   explicit CursorProxyMojo(service_manager::Connector* connector);
   ~CursorProxyMojo() override;
 
  private:
   // DrmCursorProxy.
   void CursorSet(gfx::AcceleratedWidget window,
                  const std::vector<SkBitmap>& bitmaps,
                  const gfx::Point& point,
                  int frame_delay_ms) override;
   void Move(gfx::AcceleratedWidget window, const gfx::Point& point) override;
-  void InitializeOnEvdev() override;
+  void InitializeOnEvdevIfNecessary() override;
 
   std::unique_ptr<service_manager::Connector> connector_;
 
   // Mojo implementation of the DrmCursorProxy.
   ui::ozone::mojom::DeviceCursorPtr main_cursor_ptr_;
   ui::ozone::mojom::DeviceCursorPtr evdev_cursor_ptr_;
 
-  base::PlatformThreadRef evdev_ref_;
+  base::PlatformThreadRef ui_thread_ref_;
+  DISALLOW_COPY_AND_ASSIGN(CursorProxyMojo);
 };
 
 }  // namespace ui
 
 #endif  // UI_OZONE_PLATFORM_DRM_CURSOR_PROXY_MOJO_H_