Fix a threading bug in the brlapi basec braille controller

This CL enables brlapi support by default in builds for chromeos (it's already enabled by default in chromeos itself, so that part is a noop). This revealed a threading bug in the implementation which is also fixed my moving a file_path_watcher from the IO thread to the FILE threadd.

BUG=178559

Review URL: https://chromiumcodereview.appspot.com/24325002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225008 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 225008
Revert 224987 "Fix crash when showing error in wrench menu"

Android unit_test failures are real:
http://build.chromium.org/p/chromium.linux/builders/Android%20Tests/builds/8139/steps/unit_tests/logs/stdio#failure1

[----------] 3 tests from ProfileSyncServiceAutofillTest
[ RUN      ] ProfileSyncServiceAutofillTest.HasProfileEmptySync
[FATAL:global_error_service.cc(26)] Check failed: error. 
[FATAL:global_error_service.cc(26)] Check failed: error. 
[ CRASHED      ]

> Fix crash when showing error in wrench menu
>
> This is speculative fix for a crash in
> WrenchMenuModel::AddGlobalErrorMenuItems(). My guess is that we're
> modifying a list while iterating over it. Fix is to move the modifying
> call out of the loop.
>
> BUG=278543
> TEST=Can't repro the crash. Just built and ran Chrome.
> NOTRY=true
>
> Review URL: https://chromiumcodereview.appspot.com/23435011

TBR=sail@chromium.org

Review URL: https://codereview.chromium.org/23439011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225009 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 225009