Ability to remove handlers from worker-channel and metadata-manager

www/common/make-backup.js

@@ -92,12 +92,11 @@ define([
         var opts = {
             password: pData.password
         };
-        var done = false;
-        ctx.sframeChan.on("EV_CRYPTGET_PROGRESS", function (data) {
-            if (done || data.hash !== parsed.hash) { return; }
+        var handler = ctx.sframeChan.on("EV_CRYPTGET_PROGRESS", function (data) {
+            if (data.hash !== parsed.hash) { return; }
             updateProgress.progress(data.progress);
             if (data.progress === 1) {
-                done = true;
+                handler.stop();
                 updateProgress.progress2(1);
             }
         });

www/common/metadata-manager.js

@@ -194,6 +194,15 @@ define(['json.sortify'], function (Sortify) {
             onChange: function (f) { changeHandlers.push(f); },
             onChangeLazy: function (f) { lazyChangeHandlers.push(f); },
             onRequestSync: function (f) { syncHandlers.push(f); },
+            off: function (name, f) {
+                var h = [];
+                if (name === 'change') { h = changeHandlers; }
+                else if (name === 'lazy') { h = lazyChangeHandlers; }
+                else if (name === 'title') { h = titleChangeHandlers; }
+                else if (name === 'sync') { h = syncHandlers; }
+                var idx = h.indexOf(f);
+                if (idx !== -1) { h.splice(idx, 1); }
+            },
             isConnected : function () {
                 return members.indexOf(meta.user.netfluxId) !== -1;
             },

www/common/outer/worker-channel.js

@@ -81,17 +81,25 @@ define([
         // If the type is a query, your handler will be invoked with a reply function that takes
         // one argument (the content to reply with).
         chan.on = function (queryType, handler, quiet) {
-            (handlers[queryType] = handlers[queryType] || []).push(function (data, msg) {
+            var h = function (data, msg) {
                 handler(data.content, function (replyContent) {
                     postMsg(JSON.stringify({
                         txid: data.txid,
                         content: replyContent
                     }));
                 }, msg);
-            });
+            };
+            (handlers[queryType] = handlers[queryType] || []).push(h);
             if (!quiet) {
                 event('EV_REGISTER_HANDLER', queryType);
             }
+            return {
+                stop: function () {
+                    var idx = handlers[queryType].indexOf(h);
+                    if (idx === -1) { return; }
+                    handlers[queryType].splice(idx, 1);
+                }
+            };
         };
 
         // If a particular handler is registered, call the callback immediately, otherwise it will be called