feat(external_api,devices) drop use of isDeviceListAvailable

It's always true.

conference.js

@@ -2069,8 +2069,7 @@ export default {
     _initDeviceList(setDeviceListChangeHandler = false) {
         const { mediaDevices } = JitsiMeetJS;
 
-        if (mediaDevices.isDeviceListAvailable()
-                && mediaDevices.isDeviceChangeAvailable()) {
+        if (mediaDevices.isDeviceChangeAvailable()) {
             if (setDeviceListChangeHandler) {
                 this.deviceChangeListener = devices =>
                     window.setTimeout(() => this._onDeviceListChanged(devices), 0);

modules/API/external/external_api.js

@@ -11,7 +11,6 @@ import {
     getAvailableDevices,
     getCurrentDevices,
     isDeviceChangeAvailable,
-    isDeviceListAvailable,
     isMultipleAudioInputSupported,
     setAudioInputDevice,
     setAudioOutputDevice,
@@ -989,10 +988,15 @@ export default class JitsiMeetExternalAPI extends EventEmitter {
      * Returns Promise that resolves with true if the device list is available
      * and with false if not.
      *
+     * @deprecated
+     *
      * @returns {Promise}
      */
     isDeviceListAvailable() {
-        return isDeviceListAvailable(this._transport);
+        console.warn('isDeviceListAvailable is deprecated and will be removed in the future. '
+                     + 'It always returns true');
+
+        return Promise.resolve(true);
     }
 
     /**

modules/API/external/functions.js

@@ -56,21 +56,6 @@ export function isDeviceChangeAvailable(transport, deviceType) {
     });
 }
 
-/**
- * Returns Promise that resolves with true if the device list is available
- * and with false if not.
- *
- * @param {Transport} transport - The @code{Transport} instance responsible for
- * the external communication.
- * @returns {Promise}
- */
-export function isDeviceListAvailable(transport) {
-    return transport.sendRequest({
-        type: 'devices',
-        name: 'isDeviceListAvailable'
-    });
-}
-
 /**
  * Returns Promise that resolves with true if multiple audio input is supported
  * and with false if not.

react/features/base/devices/actions.web.ts

@@ -150,8 +150,7 @@ export function getAvailableDevices() {
     return (dispatch: IStore['dispatch'], getState: IStore['getState']) => new Promise(resolve => {
         const { mediaDevices } = JitsiMeetJS;
 
-        if (mediaDevices.isDeviceListAvailable()
-                && mediaDevices.isDeviceChangeAvailable()) {
+        if (mediaDevices.isDeviceChangeAvailable()) {
             mediaDevices.enumerateDevices((devices: MediaDeviceInfo[]) => {
                 const { filteredDevices, ignoredDevices } = filterIgnoredDevices(devices);
                 const oldDevices = flattenAvailableDevices(getState()['features/base/devices'].availableDevices);

react/features/device-selection/functions.web.ts

@@ -163,7 +163,8 @@ export function processExternalDeviceRequest( // eslint-disable-line max-params
 
     switch (request.name) {
     case 'isDeviceListAvailable':
-        responseCallback(JitsiMeetJS.mediaDevices.isDeviceListAvailable());
+        // TODO(saghul): remove this, eventually.
+        responseCallback(true);
         break;
     case 'isDeviceChangeAvailable':
         responseCallback(