Issue 1724 - Fixed memory leak in messaging code, when no response is sent, on Safari

safari/ext/common.js

Index: safari/ext/common.js
===================================================================
--- a/safari/ext/common.js
+++ b/safari/ext/common.js
@@ -31,19 +31,35 @@
       var response = {};
       for (var prop in request)
         response[prop] = request[prop];
-      response.payload = message;
+      if (typeof message != "undefined")
+        response.payload = message;
 
       this._messageDispatcher.dispatchMessage("response", response);
     },
     handleRequest: function(request, sender)
     {
-      var sendResponse;
       if ("callbackId" in request)
-        sendResponse = this._sendResponse.bind(this, request);
+      {
+        var sent = false;
+        var sendResponse = function(message)
+        {
+          this._sendResponse(request, message);
+          sent = true;
+        }.bind(this);
+
+        var results = ext.onMessage._dispatch(request.payload, sender, sendResponse);
+
+        // The onMessage listener has to return true to indicate that a response
+        // is sent later asynchronously. Otherwise if no response was sent yet,
+        // we sent a response indicating that there is no response, that
+        // the other end can remove the callback and doesn't leak memory.
+        if (!sent && results.indexOf(true) == -1)
+          this._sendResponse(request, undefined);
+      }
       else
-        sendResponse = function() {};
-
-      ext.onMessage._dispatch(request.payload, sender, sendResponse);
+      {
+        ext.onMessage._dispatch(request.payload, sender, function() {});
+      }
     },
     handleResponse: function(response)
     {
@@ -52,7 +68,9 @@
       if (callback)
       {
         delete this._responseCallbacks[callbackId];
-        callback(response.payload);
+
+        if ("payload" in response)
+          callback(response.payload);
       }
     },
     sendMessage: function(message, responseCallback, extra)