Creating an IOThread outside of a full Chrome environment requires a
fair bit of weirdness, and I'm running into DCHECKs in another CL in
the IOThread unit test test fixture.  Rather than try and debug it,
it's simpler just to convert them to browser tests and not support
unit testing of IOThread (Which is going away at some point, anyways).

IOThreadTestWithIOThreadObject.UpdateAuthAndroidNegotiateAccountType
is Android only, so can't be tested in a browser test. This CL just
removes it, which is a bit unfortunate, though the test only checks
that prefs::kAuthAndroidNegotiateAccountType make it to
http_auth_preferences.

Bug: 754007
Change-Id: Ifddd5fb3dcd6d20a36352ed749b3fd5614c68289
Reviewed-on: https://chromium-review.googlesource.com/764687


Commit-Queue: Matt Menke <mmenke@chromium.org>
Reviewed-by: Tarun Bansal <tbansal@chromium.org>
Reviewed-by: Asanka Herath <asanka@chromium.org>
Cr-Commit-Position: refs/heads/master@{#516143}