GitLab

Get the path of the plugin interposing library from the embedder, since they're the ones who bundle it. Make content still work without it. This allows plugins to work inside content_shell.

BUG=90448
Review URL: https://chromiumcodereview.appspot.com/10806075

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@147965 0039d316-1c4b-4281-b951-d872f2087c98