Don't allow extensions to take screenshots of interstitial pages. Branched from
https://codereview.chromium.org/14885004/ which is trying to test it.

BUG=229504

Review URL: https://chromiumcodereview.appspot.com/14954004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@198297 0039d316-1c4b-4281-b951-d872f2087c98
void TabsDetectLanguageFunction::Observe(
    int type,
    const content::NotificationSource& source,
    const content::NotificationDetails& details) {
  std::string language;
  if (type == chrome::NOTIFICATION_TAB_LANGUAGE_DETERMINED)
    language = *content::Details<std::string>(details).ptr();

  registrar_.RemoveAll();

  GotLanguage(language);
}

void TabsDetectLanguageFunction::Observe(
    int type,
    const content::NotificationSource& source,
    const content::NotificationDetails& details) {
  std::string language;
  if (type == chrome::NOTIFICATION_TAB_LANGUAGE_DETERMINED)
    language = *content::Details<std::string>(details).ptr();

  registrar_.RemoveAll();

  GotLanguage(language);
}
