code: static String makeLayout(String descriptor, String blockName, boolean useUBO)
      {
          return NativeShaderManager.makeLayout(descriptor, blockName, useUBO);
      }
docs: Make a string with the shader layout for a uniform block
  with a given descriptor. The format of the descriptor is
  the same as for a @{link GVRShaderData} - a string of
  types and names of each field.
  <p>
  This function will return a Vulkan shader layout if the
  Vulkan renderer is being used. Otherwise, it returns
  an OpenGL layout.
  @param descriptor string with types and names of each field
  @param blockName  name of uniform block
  @param useUBO     true to output uniform buffer layout, false for push constants
  @return string with shader declaration