Remove TabContents from TabStripModelObserver::TabDetachedAt.

BUG=107201
TEST=no visible change


Review URL: https://chromiumcodereview.appspot.com/11293205

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@167122 0039d316-1c4b-4281-b951-d872f2087c98
void ExtensionUnloadNotificationObserver::Observe(
    int type, const content::NotificationSource& source,
    const content::NotificationDetails& details) {
  if (type == chrome::NOTIFICATION_EXTENSION_UNLOADED) {
    did_receive_unload_notification_ = true;
  } else {
    NOTREACHED();
  }
}

void ExtensionUnloadNotificationObserver::Observe(
    int type, const content::NotificationSource& source,
    const content::NotificationDetails& details) {
  if (type == chrome::NOTIFICATION_EXTENSION_UNLOADED) {
    did_receive_unload_notification_ = true;
  } else {
    NOTREACHED();
  }
}
