This ivar was passed to the thread function for the private state thread
- mostly because the equivalent variable was passed in in the original
version of the code. But it was never used, so I didn't notice that the
ivar equivalent wasn't being initialized. I'm going to keep the ivar
because it will be useful when debugging to easily see whether you are
on the main or secondary private state thread.
So in this change, I set m_is_secondary_thread properly in the
constructor, but remove passing it to the thread function since it
wasn't needed there.
6bdb7b0f00