process both have a
   * Chrome_ChildIOThread.
   *
   * This is a function instead of just a variable because the test functions
   * are meant to modify this modelSpec and insert suitable expectations.
   *
   * The modelSpec includes a basic browser process because it not a valid
   * chrome model otherwise.
   *
   * The renderer ChildIOThread looks like
   *
   * |0    |10   |20   |30   |40   |50   |60   |70  .... Time
   * [     ]     [     ]     [     ]     [     ]    .... Slices
   *
   * where each