Adds helper function to obtain large video id from tests.

modules/UI/UI.js

@@ -790,4 +790,12 @@ UI.onStartMutedChanged = function () {
     SettingsMenu.onStartMutedChanged();
 };
 
+/**
+ * Returns the id of the current video shown on large.
+ * Currently used by tests (troture).
+ */
+UI.getLargeVideoID = function () {
+    return VideoLayout.getLargeVideoID();
+};
+
 module.exports = UI;

modules/UI/videolayout/VideoLayout.js

@@ -1027,6 +1027,14 @@ var VideoLayout = {
 
     isLargeContainerTypeVisible (type) {
         return largeVideo && largeVideo.state === type;
+    },
+
+    /**
+     * Returns the id of the current video shown on large.
+     * Currently used by tests (troture).
+     */
+    getLargeVideoID () {
+        return largeVideo.id;
     }
 };