1 files changed, 100 insertions, 0 deletions
diff --git a/browser/components/newtab/lib/ActivityStreamPrefs.sys.mjs b/browser/components/newtab/lib/ActivityStreamPrefs.sys.mjs
new file mode 100644
index 0000000000..192ff30288
--- /dev/null
+++ b/browser/components/newtab/lib/ActivityStreamPrefs.sys.mjs
@@ -0,0 +1,100 @@
+/* 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/. */
+
+// We use importESModule here instead of static import so that
+// the Karma test environment won't choke on this module. This
+// is because the Karma test environment already stubs out
+// AppConstants, and overrides importESModule to be a no-op (which
+// can't be done for a static import statement).
+
+// eslint-disable-next-line mozilla/use-static-import
+const { AppConstants } = ChromeUtils.importESModule(
+  "resource://gre/modules/AppConstants.sys.mjs"
+);
+// eslint-disable-next-line mozilla/use-static-import
+const { Preferences } = ChromeUtils.importESModule(
+  "resource://gre/modules/Preferences.sys.mjs"
+);
+
+const ACTIVITY_STREAM_PREF_BRANCH = "browser.newtabpage.activity-stream.";
+
+export class Prefs extends Preferences {
+  /**
+   * Prefs - A wrapper around Preferences that always sets the branch to
+   *         ACTIVITY_STREAM_PREF_BRANCH
+   */
+  constructor(branch = ACTIVITY_STREAM_PREF_BRANCH) {
+    super({ branch });
+    this._branchObservers = new Map();
+  }
+
+  ignoreBranch(listener) {
+    const observer = this._branchObservers.get(listener);
+    this._prefBranch.removeObserver("", observer);
+    this._branchObservers.delete(listener);
+  }
+
+  observeBranch(listener) {
+    const observer = (subject, topic, pref) => {
+      listener.onPrefChanged(pref, this.get(pref));
+    };
+    this._prefBranch.addObserver("", observer);
+    this._branchObservers.set(listener, observer);
+  }
+}
+
+export class DefaultPrefs extends Preferences {
+  /**
+   * DefaultPrefs - A helper for setting and resetting default prefs for the add-on
+   *
+   * @param  {Map} config A Map with {string} key of the pref name and {object}
+   *                      value with the following pref properties:
+   *         {string} .title (optional) A description of the pref
+   *         {bool|string|number} .value The default value for the pref
+   * @param  {string} branch (optional) The pref branch (defaults to ACTIVITY_STREAM_PREF_BRANCH)
+   */
+  constructor(config, branch = ACTIVITY_STREAM_PREF_BRANCH) {
+    super({
+      branch,
+      defaultBranch: true,
+    });
+    this._config = config;
+  }
+
+  /**
+   * init - Set default prefs for all prefs in the config
+   */
+  init() {
+    // Local developer builds (with the default mozconfig) aren't OFFICIAL
+    const IS_UNOFFICIAL_BUILD = !AppConstants.MOZILLA_OFFICIAL;
+
+    for (const pref of this._config.keys()) {
+      try {
+        // Avoid replacing existing valid default pref values, e.g., those set
+        // via Autoconfig or policy
+        if (this.get(pref) !== undefined) {
+          continue;
+        }
+      } catch (ex) {
+        // We get NS_ERROR_UNEXPECTED for prefs that have a user value (causing
+        // default branch to believe there's a type) but no actual default value
+      }
+
+      const prefConfig = this._config.get(pref);
+      let value;
+      if (IS_UNOFFICIAL_BUILD && "value_local_dev" in prefConfig) {
+        value = prefConfig.value_local_dev;
+      } else {
+        value = prefConfig.value;
+      }
+
+      try {
+        this.set(pref, value);
+      } catch (ex) {
+        // Potentially the user somehow set an unexpected value type, so we fail
+        // to set a default of our expected type
+      }
+    }
+  }
+}