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 TabStripModel::SetSelectionFromModel(
    const TabStripSelectionModel& source) {
  DCHECK_NE(TabStripSelectionModel::kUnselectedIndex, source.active());
  SetSelection(source, NOTIFY_DEFAULT);
}

void TabStripModel::SetSelectionFromModel(
    const TabStripSelectionModel& source) {
  DCHECK_NE(TabStripSelectionModel::kUnselectedIndex, source.active());
  SetSelection(source, NOTIFY_DEFAULT);
}
