[WebsiteSettings] Fix bug in permission bubble manager to alter showing state when bubble is closed.

This bug meant that subsequent calls to AddRequest wouldn't show the bubble, since the manager still believed it was being shown.

R=leng@chromium.org

Review URL: https://codereview.chromium.org/162423002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251397 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 251397