Make ozone/drm/mojo more immune to startup races

ui/ozone/platform/drm/host/drm_cursor.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_DRM_HOST_DRM_CURSOR_H_
 #define UI_OZONE_PLATFORM_DRM_HOST_DRM_CURSOR_H_
 
 #include <memory>
 #include <vector>
 
@@ skipping 16 matching lines @@
 
   // Sets the cursor |bitmaps| on |window| at |point| with |frame_delay_ms|.
   virtual void CursorSet(gfx::AcceleratedWidget window,
                          const std::vector<SkBitmap>& bitmaps,
                          const gfx::Point& point,
                          int frame_delay_ms) = 0;
   // Moves the cursor in |window| to |point|.
   virtual void Move(gfx::AcceleratedWidget window, const gfx::Point& point) = 0;
 
   // Initialize EvdevThread-specific state.
-  virtual void InitializeOnEvdev() = 0;
+  virtual void InitializeOnEvdevIfNecessary() = 0;
 };
 
 // DrmCursor manages all cursor state and semantics.
 class DrmCursor : public CursorDelegateEvdev {
  public:
   explicit DrmCursor(DrmWindowHostManager* window_manager);
   ~DrmCursor() override;
 
-  // Sets or resets the DrmProxy |proxy|. If |proxy| is set, the DrmCursor uses
-  // it to communicate to the GPU process or thread.
-  void SetDrmCursorProxy(DrmCursorProxy* proxy);
+  // Sets or the DrmProxy |proxy|. If |proxy| is set, the DrmCursor uses
+  // it to communicate to the GPU process or thread. Returns the previous
+  // value.
+  void SetDrmCursorProxy(std::unique_ptr<DrmCursorProxy> proxy);
   void ResetDrmCursorProxy();
 
   // Change the cursor over the specifed window.
   void SetCursor(gfx::AcceleratedWidget window, PlatformCursor platform_cursor);
 
   // Handle window lifecycle.
   void OnWindowAdded(gfx::AcceleratedWidget window,
                      const gfx::Rect& bounds_in_screen,
                      const gfx::Rect& cursor_confined_bounds);
   void OnWindowRemoved(gfx::AcceleratedWidget window);
@@ skipping 54 matching lines @@
   DrmWindowHostManager* window_manager_;  // Not owned.
 
   std::unique_ptr<DrmCursorProxy> proxy_;
 
   DISALLOW_COPY_AND_ASSIGN(DrmCursor);
 };
 
 }  // namespace ui
 
 #endif  // UI_OZONE_PLATFORM_DRM_HOST_DRM_CURSOR_H_