Revert 226509 "Media Galleries API: Fix MediaGalleriesPreference..."

> Media Galleries API: Fix MediaGalleriesPreferences initialization for fresh profiles.
> 
> BUG=151701, 295880
> R=vandebo@chromium.org
> 
> Review URL: https://codereview.chromium.org/25539003

TBR=tommycli@chromium.org

Review URL: https://codereview.chromium.org/25725004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226517 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226517