Issue 3853 - Use new messaging API for the first-run page

lib/child/cssProperties.js

Index: lib/child/cssProperties.js
===================================================================
--- a/lib/child/cssProperties.js
+++ b/lib/child/cssProperties.js
@@ -24,23 +24,23 @@
   let {port} = require("messaging");
   let {getFrames} = require("child/utils");
 
   let senderWindow = null;
 
   let scope = {
     ext: {
       backgroundPage: {
-        sendMessage: function(data, callback)
+        sendMessage: function(payload, callback)
         {
-          data = {payload: data, frames: getFrames(senderWindow)};
+          let message = {payload, frames: getFrames(senderWindow)};
           if (typeof callback == "function")
-            port.emitWithResponse("cssPropertiesRequest", data).then(callback);
+            port.emitWithResponse("ext_message", message).then(callback);
           else
-            port.emit("cssPropertiesRequest", data);
+            port.emit("ext_message", message);
         }
       }
     }
   };
 
   function loadScript(script)
   {
     Services.scriptloader.loadSubScript(script, scope);