GitLab

switch mediaGalleries to .idl api definition

BUG=none
TEST=manual
TBR=asargent

Review URL: https://chromiumcodereview.appspot.com/10800083

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@148011 0039d316-1c4b-4281-b951-d872f2087c98