Detect phantom tabs using PING in the worker

www/common/cryptpad-common.js

@@ -1058,14 +1058,12 @@ define([
     };
 
     var timeout = false;
+    common.onTimeoutEvent = Util.mkEvent();
     var onTimeout = function () {
-        return;
-        /*
         timeout = true;
         common.onNetworkDisconnect.fire();
-        // FIXME: no UI in outer...
-        window.alert("Timeout error, please reload this tab");
-        */
+        common.padRpc.onDisconnectEvent.fire();
+        common.onTimeoutEvent.fire();
     };
 
     var queries = {

www/common/outer/async-store.js

@@ -1602,12 +1602,11 @@ define([
                 broadcast([], 'NETWORK_RECONNECT', {myId: info.myId});
             });
 
-            /*
             // Ping clients regularly to make sure one tab was not closed without sending a removeClient()
             // command. This allow us to avoid phantom viewers in pads.
             var PING_INTERVAL = 30000;
-            var MAX_PING = 1000;
-            var MAX_FAILED_PING = 5;
+            var MAX_PING = 5000;
+            var MAX_FAILED_PING = 2;
 
             setInterval(function () {
                 var clients = [];
@@ -1635,7 +1634,6 @@ define([
                     ping();
                 });
             }, PING_INTERVAL);
-            */
         };
 
         /**

www/common/sframe-common-outer.js

@@ -874,6 +874,10 @@ define([
                 Cryptpad.cursor.execCommand(data, cb);
             });
 
+            Cryptpad.onTimeoutEvent.reg(function () {
+                sframeChan.event('EV_WORKER_TIMEOUT');
+            });
+
             if (cfg.messaging) {
                 Notifier.getPermission();
 

www/common/sframe-common.js

@@ -613,6 +613,10 @@ define([
                 });
             });
 
+            ctx.sframeChan.on('EV_WORKER_TIMEOUT', function () {
+                UI.errorLoadingScreen(Messages.timeoutError) // XXX
+            });
+
             ctx.sframeChan.on('EV_CHROME_68', function () {
                 UI.alert(Messages.chrome68);
             });