Etherpad on join (#8212)

* Add option to open Etherpad on join

For sites that focus on collaborative editing during meetings, add
an option which, when set, will automatically open etherpad when a
participant joins.

* Add openSharedDocumentOnJoin to config whitelist

This also adds some config file doc comments about the option,
including a note about the choice not to honor it in the mobile app.

config.js

@@ -367,6 +367,13 @@ var config = {
     // When 'true', it shows an intermediate page before joining, where the user can configure their devices.
     // prejoinPageEnabled: false,
 
+    // If etherpad integration is enabled, setting this to true will
+    // automatically open the etherpad when a participant joins.  This
+    // does not affect the mobile app since opening an etherpad
+    // obscures the conference controls -- it's better to let users
+    // choose to open the pad on their own in that case.
+    // openSharedDocumentOnJoin: false,
+
     // If true, shows the unsafe room name warning label when a room name is
     // deemed unsafe (due to the simplicity in the name) and a password is not
     // set or the lobby is not enabled.

modules/UI/UI.js

@@ -221,6 +221,10 @@ UI.initEtherpad = name => {
     const url = new URL(name, config.etherpad_base);
 
     APP.store.dispatch(setDocumentUrl(url.toString()));
+
+    if (config.openSharedDocumentOnJoin) {
+        etherpadManager.toggleEtherpad();
+    }
 };
 
 /**

react/features/base/config/configWhitelist.js

@@ -129,6 +129,7 @@ export default [
     'localRecording',
     'maxFullResolutionParticipants',
     'openBridgeChannel',
+    'openSharedDocumentOnJoin',
     'opusMaxAverageBitrate',
     'p2p',
     'pcStatsInterval',