don't use params to switch actionType

react/features/local-recording/actions.js

     LOCAL_RECORDING_STATS_UPDATE
 } from './actionTypes';
 
+// The following two actions signal state changes in local recording engagement.
+// In other words, the events of the local WebWorker / MediaRecorder starting to
+// record and finishing recording.
+// Note that this is not the event fired when the users tries to start the
+// recording in the UI.
+
 /**
- * Signals state change in local recording engagement.
- * In other words, the events of the local WebWorker / MediaRecorder
- * starting to record and finishing recording.
- *
- * Note that this is not the event fired when the users tries to start
- * the recording in the UI.
+ * Signals that local recording has started.
  *
- * @param {bool} isEngaged - Whether local recording is engaged or not.
  * @returns {{
  *     type: LOCAL_RECORDING_ENGAGED
- * }|{
+ * }}
+ */
+export function localRecordingEngaged() {
+    return {
+        type: LOCAL_RECORDING_ENGAGED
+    };
+}
+
+/**
+ * Signals that local recording has finished.
+ *
+ * @returns {{
  *     type: LOCAL_RECORDING_UNENGAGED
  * }}
  */
-export function signalLocalRecordingEngagement(isEngaged: boolean) {
+export function localRecordingUnengaged() {
     return {
-        type: isEngaged ? LOCAL_RECORDING_ENGAGED : LOCAL_RECORDING_UNENGAGED
+        type: LOCAL_RECORDING_UNENGAGED
     };
 }
 

react/features/local-recording/middleware.js

 import { MiddlewareRegistry } from '../base/redux';
 import { showNotification } from '../notifications';
 
+import { localRecordingEngaged, localRecordingUnengaged } from './actions';
 import { recordingController } from './controller';
-import { signalLocalRecordingEngagement } from './actions';
 
 MiddlewareRegistry.register(({ getState, dispatch }) => next => action => {
     const result = next(action);
         break;
     }
     case APP_WILL_MOUNT:
-        // realize the delegates on recordingController,
-        // providing UI reactions.
-        recordingController.onStateChanged = function(state) {
-            dispatch(signalLocalRecordingEngagement(state));
+        // realize the delegates on recordingController, allowing the UI to
+        // react to state changes in recordingController.
+        recordingController.onStateChanged = function(isEngaged) {
+            if (isEngaged) {
+                dispatch(localRecordingEngaged());
+            } else {
+                dispatch(localRecordingUnengaged());
+            }
         };
 
         recordingController.onWarning = function(message) {