[Contextual Search] Change "Now on Tap" to "Contextual Cards"

BUG=644934

Review-Url: https://codereview.chromium.org/2361163003
Cr-Commit-Position: refs/heads/master@{#420899}
size_t TemplateURLRef::GetSearchTermPositionInPath(
    const SearchTermsData& search_terms_data) const {
  ParseIfNecessary(search_terms_data);
  return search_term_position_in_path_;
}

size_t TemplateURLRef::GetSearchTermPositionInPath(
    const SearchTermsData& search_terms_data) const {
  ParseIfNecessary(search_terms_data);
  return search_term_position_in_path_;
}
