[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}
std::vector<std::string> RegisterAllFeatureVariationParameters(
    flags_ui::FlagsStorage* flags_storage,
    base::FeatureList* feature_list) {
  return FlagsStateSingleton::GetFlagsState()
      ->RegisterAllFeatureVariationParameters(flags_storage, feature_list);
}

std::vector<std::string> RegisterAllFeatureVariationParameters(
    flags_ui::FlagsStorage* flags_storage,
    base::FeatureList* feature_list) {
  return FlagsStateSingleton::GetFlagsState()
      ->RegisterAllFeatureVariationParameters(flags_storage, feature_list);
}
