Make it clear that the logger methods are used by xblocks.

common/static/js/spec/logger_spec.js

@@ -6,6 +6,8 @@
         });
 
         describe('log', function() {
+            // Note that log is used by external XBlocks, and the API cannot change without
+            // proper deprecation and notification for external authors.
             it('can send a request to log event', function() {
                 spyOn(jQuery, 'ajaxWithPrefix');
                 Logger.log('example', 'data');
@@ -106,6 +108,8 @@
         });
 
         describe('listen', function() {
+            // Note that listen is used by external XBlocks, and the API cannot change without
+            // proper deprecation and notification for external authors.
             beforeEach(function () {
                 spyOn(jQuery, 'ajaxWithPrefix');
                 this.callbacks = _.map(_.range(4), function () {
@@ -146,6 +150,8 @@
         });
 
         describe('bind', function() {
+            // Note that bind may be used by external XBlocks, and the API cannot change without
+            // proper deprecation and notification for external authors.
             beforeEach(function() {
                 this.initialPostWithPrefix = jQuery.postWithPrefix;
                 this.initialGetWithPrefix = jQuery.getWithPrefix;

common/static/js/src/logger.js

@@ -24,6 +24,9 @@
         return {
             /**
              * Emits an event.
+             *
+             * Note that this method is used by external XBlocks, and the API cannot change without
+             * proper deprecation and notification for external authors.
              */
             log: function(eventType, data, element, requestOptions) {
                 var callbacks;
@@ -62,7 +65,10 @@
 
             /**
              * Adds a listener. If you want any element to trigger this listener,
-             * do element = null
+             * do element = null.
+             *
+             * Note that this method is used by external XBlocks, and the API cannot change without
+             * proper deprecation and notification for external authors.
              */
             listen: function(eventType, element, callback) {
                 listeners[eventType] = listeners[eventType] || {};
@@ -72,6 +78,9 @@
 
             /**
              * Binds `page_close` event.
+             *
+             * Note that this method is used by external XBlocks, and the API cannot change without
+             * proper deprecation and notification for external authors.
              */
             bind: function() {
                 window.onunload = function() {