Adds logic that disables accessibility under these circumstances:
* There are 3+ user input events in web content (mouse down, key down,
  or touch start count)
* Over a period of more than 30 seconds
* And no usage of accessibility APIs in that time.

The goal of this logic is to avoid disabling accessibility
simply due to inactivity, i.e. the browser is idle - but instead
to try to disable accessibility when there's evidence that the
user is actively using their browser but no longer using assistive
technology or anything else using accessibiltiy APIs.