Bug 1552280 - Update default 68+ about:welcome experience including cards for return-to-AMO r=k88hudson

Differential Revision: https://phabricator.services.mozilla.com/D35287

--HG--
extra : moz-landing-system : lando

browser/app/profile/firefox.js

@@ -1321,11 +1321,7 @@ pref("browser.newtabpage.activity-stream.improvesearch.handoffToAwesomebar", tru
 pref("browser.newtabpage.activity-stream.improvesearch.handoffToAwesomebar", false);
 #endif
 
-#ifdef NIGHTLY_BUILD
 pref("trailhead.firstrun.branches", "join-privacy");
-#else
-pref("trailhead.firstrun.branches", "control");
-#endif
 
 // Enable the DOM fullscreen API.
 pref("full-screen-api.enabled", true);

browser/components/newtab/lib/ASRouter.jsm

@@ -724,6 +724,11 @@ class _ASRouter {
     let interrupt;
     let triplet;
 
+    // Use control Trailhead Branch (for cards) if we are showing RTAMO.
+    if (await this._hasAddonAttributionData()) {
+      return {experiment, interrupt: "control", triplet: ""};
+    }
+
     // If a value is set in TRAILHEAD_OVERRIDE_PREF, it will be returned and no experiment will be set.
     const overrideValue = Services.prefs.getStringPref(TRAILHEAD_CONFIG.OVERRIDE_PREF, "");
     if (overrideValue) {
@@ -733,7 +738,7 @@ class _ASRouter {
 
     const locale = Services.locale.appLocaleAsLangTag;
 
-    if (TRAILHEAD_CONFIG.LOCALES.includes(locale) && !(await this._hasAddonAttributionData())) {
+    if (TRAILHEAD_CONFIG.LOCALES.includes(locale)) {
       const {userId} = ClientEnvironment;
       experiment = await chooseBranch(`${userId}-trailhead-experiments`, TRAILHEAD_CONFIG.EXPERIMENT_RATIOS);