Change DesktopRootWindowHostTizenX11 from DesktopRootWindowHostXwalk.

After this CL, only Tizen(tizenos=1) uses DesktopRootWindowHostTizenX11. Desktop
linux uses DesktopRootWindowHostX11.
We have changed and will change DesktopRootWindowHostTizenX11 only for Tizen, so
only Tizen should use this class.