Update owners of chrome/browser/chromeos/accessibility.

dtseng and plundblad are now primary owners, zork and hashimoto are no
longer working on accessibility.

BUG=none
R=zork@chromium.org

Review URL: https://codereview.chromium.org/102963008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@243161 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/chromeos/accessibility/OWNERS

 dmazzoni@chromium.org
-hashimoto@chromium.org
-zork@chromium.org
+dtseng@chromium.org
+plundblad@chromium.org