1 files changed, 163 insertions, 0 deletions
diff --git a/browser/components/preferences/experimental.js b/browser/components/preferences/experimental.js
new file mode 100644
index 0000000000..266aeabc4f
--- /dev/null
+++ b/browser/components/preferences/experimental.js
@@ -0,0 +1,163 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* import-globals-from preferences.js */
+
+var gExperimentalPane = {
+  inited: false,
+  _template: null,
+  _featureGatesContainer: null,
+  _boundRestartObserver: null,
+  _observedPrefs: [],
+  _shouldPromptForRestart: true,
+
+  _featureGatePrefTypeToPrefServiceType(featureGatePrefType) {
+    if (featureGatePrefType != "boolean") {
+      throw new Error("Only boolean FeatureGates are supported");
+    }
+    return "bool";
+  },
+
+  async _observeRestart(aSubject, aTopic, aData) {
+    if (!this._shouldPromptForRestart) {
+      return;
+    }
+    let prefValue = Services.prefs.getBoolPref(aData);
+    let buttonIndex = await confirmRestartPrompt(prefValue, 1, true, false);
+    if (buttonIndex == CONFIRM_RESTART_PROMPT_RESTART_NOW) {
+      Services.startup.quit(
+        Ci.nsIAppStartup.eAttemptQuit | Ci.nsIAppStartup.eRestart
+      );
+      return;
+    }
+    this._shouldPromptForRestart = false;
+    Services.prefs.setBoolPref(aData, !prefValue);
+    this._shouldPromptForRestart = true;
+  },
+
+  addPrefObserver(name, fn) {
+    this._observedPrefs.push({ name, fn });
+    Services.prefs.addObserver(name, fn);
+  },
+
+  removePrefObservers() {
+    for (let { name, fn } of this._observedPrefs) {
+      Services.prefs.removeObserver(name, fn);
+    }
+    this._observedPrefs = [];
+  },
+
+  // Reset the features to their default values
+  async resetAllFeatures() {
+    let features = await gExperimentalPane.getFeatures();
+    for (let feature of features) {
+      Services.prefs.setBoolPref(feature.preference, feature.defaultValue);
+    }
+  },
+
+  async getFeatures() {
+    let searchParams = new URLSearchParams(document.documentURIObject.query);
+    let definitionsUrl = searchParams.get("definitionsUrl");
+    let features = await FeatureGate.all(definitionsUrl);
+    return features.filter(f => f.isPublic);
+  },
+
+  async _sortFeatures(features) {
+    // Sort the features alphabetically by their title
+    let titles = await document.l10n.formatMessages(
+      features.map(f => {
+        return { id: f.title };
+      })
+    );
+    titles = titles.map((title, index) => [title.attributes[0].value, index]);
+    titles.sort((a, b) => a[0].toLowerCase().localeCompare(b[0].toLowerCase()));
+    // Get the features in order of sorted titles.
+    return titles.map(([, index]) => features[index]);
+  },
+
+  async init() {
+    if (this.inited) {
+      return;
+    }
+    this.inited = true;
+
+    let features = await this.getFeatures();
+    let shouldHide = !features.length;
+    document.getElementById("category-experimental").hidden = shouldHide;
+    // Cache the visibility so we can show it quicker in subsequent loads.
+    Services.prefs.setBoolPref(
+      "browser.preferences.experimental.hidden",
+      shouldHide
+    );
+    if (shouldHide) {
+      // Remove the 'experimental' category if there are no available features
+      document.getElementById("firefoxExperimentalCategory").remove();
+      if (
+        document.getElementById("categories").selectedItem?.id ==
+        "category-experimental"
+      ) {
+        // Leave the 'experimental' category if there are no available features
+        gotoPref("general");
+        return;
+      }
+    }
+
+    features = await this._sortFeatures(features);
+
+    setEventListener(
+      "experimentalCategory-reset",
+      "command",
+      gExperimentalPane.resetAllFeatures
+    );
+
+    window.addEventListener("unload", () => this.removePrefObservers());
+    this._template = document.getElementById("template-featureGate");
+    this._featureGatesContainer = document.getElementById(
+      "pane-experimental-featureGates"
+    );
+    this._boundRestartObserver = this._observeRestart.bind(this);
+    let frag = document.createDocumentFragment();
+    for (let feature of features) {
+      if (Preferences.get(feature.preference)) {
+        console.error(
+          "Preference control already exists for experimental feature '" +
+            feature.id +
+            "' with preference '" +
+            feature.preference +
+            "'"
+        );
+        continue;
+      }
+      if (feature.restartRequired) {
+        this.addPrefObserver(feature.preference, this._boundRestartObserver);
+      }
+      let template = this._template.content.cloneNode(true);
+      let description = template.querySelector(".featureGateDescription");
+      description.id = feature.id + "-description";
+      let descriptionLinks = feature.descriptionLinks || {};
+      for (let [key, value] of Object.entries(descriptionLinks)) {
+        let link = document.createElement("a");
+        link.setAttribute("data-l10n-name", key);
+        link.setAttribute("href", value);
+        link.setAttribute("target", "_blank");
+        description.append(link);
+      }
+      document.l10n.setAttributes(description, feature.description);
+      let checkbox = template.querySelector(".featureGateCheckbox");
+      checkbox.setAttribute("preference", feature.preference);
+      checkbox.id = feature.id;
+      checkbox.setAttribute("aria-describedby", description.id);
+      document.l10n.setAttributes(checkbox, feature.title);
+      frag.appendChild(template);
+      let preference = Preferences.add({
+        id: feature.preference,
+        type: gExperimentalPane._featureGatePrefTypeToPrefServiceType(
+          feature.type
+        ),
+      });
+      preference.setElementValue(checkbox);
+    }
+    this._featureGatesContainer.appendChild(frag);
+  },
+};