chromeos: fix bug where "aw snap" page replaces first tab if it was a NTP when closing window with > 1 tab.

BUG=chromium-os:12088
TEST=verify bug per bug report.
Review URL: http://codereview.chromium.org/6882058

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@83031 0039d316-1c4b-4281-b951-d872f2087c98
void TabCloseableStateWatcher::TabStripWatcher::TabClosingAt(
    TabStripModel* tab_strip_model,
    TabContentsWrapper* tab_contents,
    int index) {
  if (tab_strip_model->count() == 1)
    main_watcher_->OnTabStripChanged(browser_, true);
}

void TabCloseableStateWatcher::TabStripWatcher::TabClosingAt(
    TabStripModel* tab_strip_model,
    TabContentsWrapper* tab_contents,
    int index) {
  if (tab_strip_model->count() == 1)
    main_watcher_->OnTabStripChanged(browser_, true);
}
