ozone: Initialize a subsystem only if necessary.

ui/gfx/ozone/surface_factory_ozone.h

Index: ui/gfx/ozone/surface_factory_ozone.h
diff --git a/ui/gfx/ozone/surface_factory_ozone.h b/ui/gfx/ozone/surface_factory_ozone.h
index 9f7e72811042decaef3f23e2d452c15d014ee99e..b7eb83b3e356dd76cd7aff2571ecae7b0e462031 100644
--- a/ui/gfx/ozone/surface_factory_ozone.h
+++ b/ui/gfx/ozone/surface_factory_ozone.h
@@ -82,12 +82,9 @@ class GFX_EXPORT SurfaceFactoryOzone {
   SurfaceFactoryOzone();
   virtual ~SurfaceFactoryOzone();
 
-  // Returns the instance
+  // Returns the singleton instance.
   static SurfaceFactoryOzone* GetInstance();
 
-  // Sets the implementation delegate. Ownership is retained by the caller.
-  static void SetInstance(SurfaceFactoryOzone* impl);
-
   // Configures the display hardware. Must be called from within the GPU
   // process before the sandbox has been activated.
   virtual HardwareState InitializeHardware() = 0;