Revert 238830 "Moves the ChromeVox extension into the Chrome sou..."
Reason: Breaks check_perms (Executable bits need updating) and runhooks (third_party/liblouis/liblouis_untrusted.gyp appears to be in the wrong location)

> Moves the ChromeVox extension into the Chrome source tree.
> 
> BUG=309130
> TEST=run ChromeVox on Aura.
> R=dmazzoni@chromium.org, erg@chromium.org, thakis@chromium.org, zelidrag@chromium.org
> 
> Review URL: https://codereview.chromium.org/27748003

TBR=dtseng@google.com

Review URL: https://codereview.chromium.org/105813003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238855 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 238855