Allow add to homescreen and app banner strings to be changed via variations.

chrome/browser/banners/app_banner_settings_helper.cc

Index: chrome/browser/banners/app_banner_settings_helper.cc
diff --git a/chrome/browser/banners/app_banner_settings_helper.cc b/chrome/browser/banners/app_banner_settings_helper.cc
index fb7f13af96812c53b4036aea1e9610251b2fe13c..c93f08a677337157c77947643bd5b28f5076ca4d 100644
--- a/chrome/browser/banners/app_banner_settings_helper.cc
+++ b/chrome/browser/banners/app_banner_settings_helper.cc
@@ -81,6 +81,7 @@ const char kBannerParamsEngagementTotalKey[] = "site_engagement_total";
 const char kBannerParamsDaysAfterBannerDismissedKey[] = "days_after_dismiss";
 const char kBannerParamsDaysAfterBannerIgnoredKey[] = "days_after_ignore";
 const char kBannerSiteEngagementParamsKey[] = "use_site_engagement";
+const char kBannerParamsLanguageKey[] = "language_option";
 
 // Engagement weight assigned to direct and indirect navigations.
 // By default, a direct navigation is a page visit via ui::PAGE_TRANSITION_TYPED
@@ -674,6 +675,21 @@ void AppBannerSettingsHelper::UpdateFromFieldTrial() {
   }
 }
 
+AppBannerSettingsHelper::LanguageOption
+AppBannerSettingsHelper::GetHomescreenLanguageOption() {
+  std::string param = variations::GetVariationParamValue(
+      kBannerParamsKey, kBannerParamsLanguageKey);
+  unsigned int language_option = 0;
+
+  if (param.empty() || !base::StringToUint(param, &language_option) ||
+      language_option < LANGUAGE_OPTION_MIN ||
+      language_option > LANGUAGE_OPTION_MAX) {
+    return LANGUAGE_OPTION_DEFAULT;
+  }
+
+  return static_cast<LanguageOption>(language_option);
+}
+
 bool AppBannerSettingsHelper::ShouldUseSiteEngagementScore() {
   if (base::CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kEnableSiteEngagementAppBanner)) {