Remove use of FILE thread from braille_controller_brlapi.cc

This is part of the TaskScheduler migration, see the linked
bug and various messages on chromium-dev for context.

Bug: 689520
Test: flashed to Chromebook, plugged in braille display.

Change-Id: Id7f196ba58d5e013c516e63266d47f9307e4d2d1
Reviewed-on: https://chromium-review.googlesource.com/589776
Commit-Queue: Dominic Mazzoni <dmazzoni@chromium.org>
Reviewed-by: David Tseng <dtseng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#491520}
2 files changed