Remove double-initialization for plugin modules.
Remove double-initialization for plugin modules.

TEST=none
BUG=none
Review URL: http://codereview.chromium.org/6250179

git-svn-id: http://src.chromium.org/svn/trunk/src@73916 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 43d45f5def525baade13008a3b6d7c1006af143e
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser