Convert Ozone GL OSMesa implementation.

ui/ozone/platform/cast/surface_factory_cast.h

Index: ui/ozone/platform/cast/surface_factory_cast.h
diff --git a/ui/ozone/platform/cast/surface_factory_cast.h b/ui/ozone/platform/cast/surface_factory_cast.h
index 23d1e2213d64af6b770b7cc208a89b80e87f766f..d25688a08a796bcbab622dcee914e1244708684e 100644
--- a/ui/ozone/platform/cast/surface_factory_cast.h
+++ b/ui/ozone/platform/cast/surface_factory_cast.h
@@ -41,6 +41,7 @@ class SurfaceFactoryCast : public SurfaceFactoryOzone {
 
  private:
   std::unique_ptr<GLOzoneEglCast> egl_implementation_;
+  std::unique_ptr<GLOzone> osmesa_implementation_;
 
   DISALLOW_COPY_AND_ASSIGN(SurfaceFactoryCast);
 };