Adding the files would help

src/settings/controllers/PushToMatrixClientController.js

@@ -0,0 +1,37 @@
+/*
+Copyright 2020 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import { MatrixClientPeg } from '../../MatrixClientPeg';
+
+/**
+ * When the value changes, call a setter function on the matrix client with the new value
+ */
+export default class PushToMatrixClientController {
+    constructor(setter, inverse) {
+        this._setter = setter;
+        this._inverse = inverse;
+    }
+
+    getValueOverride(level, roomId, calculatedValue, calculatedAtLevel) {
+        return null; // no override
+    }
+
+    onChange(level, roomId, newValue) {
+        // XXX does this work? This surely isn't necessarily the effective value,
+        // but it's what NotificationsEnabledController does...
+        this._setter.call(MatrixClientPeg.get(), this._inverse ? !newValue : newValue);
+    }
+}