Bug 1817196: Record preference value that affects the number of results showing in the urlbar r=mak

Differential Revision: https://phabricator.services.mozilla.com/D170317

browser/components/urlbar/UrlbarController.sys.mjs

@@ -741,6 +741,7 @@ class TelemetryEvent {
     this._controller = controller;
     this._category = category;
     this._isPrivate = controller.input.isPrivate;
+    this.#beginObservingPingPrefs();
   }
 
   /**
@@ -1327,5 +1328,39 @@ class TelemetryEvent {
     this.#previousSearchWordsSet = null;
   }
 
+  #PING_PREFS = {
+    maxRichResults: Glean.urlbar.prefMaxResults,
+    "suggest.topsites": Glean.urlbar.prefSuggestTopsites,
+  };
+
+  #beginObservingPingPrefs() {
+    this.onPrefChanged("searchEngagementTelemetry.enabled");
+    lazy.UrlbarPrefs.addObserver(this);
+  }
+
+  onPrefChanged(pref) {
+    if (pref === "searchEngagementTelemetry.enabled") {
+      for (const p of Object.keys(this.#PING_PREFS)) {
+        this.onPrefChanged(p);
+      }
+      return;
+    }
+
+    if (!lazy.UrlbarPrefs.get("searchEngagementTelemetryEnabled")) {
+      return;
+    }
+
+    const metric = this.#PING_PREFS[pref];
+    if (metric) {
+      metric.set(lazy.UrlbarPrefs.get(pref));
+    }
+  }
+
+  onNimbusChanged(variable) {
+    if (variable === "searchEngagementTelemetryEnabled") {
+      this.onPrefChanged("searchEngagementTelemetry.enabled");
+    }
+  }
+
   #previousSearchWordsSet = null;
 }