Initial work to remove the notion of all extension message payloads as strings.

chrome/renderer/resources/extensions/event.js

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
   var eventBindingsNatives = requireNative('event_bindings');
   var AttachEvent = eventBindingsNatives.AttachEvent;
   var DetachEvent = eventBindingsNatives.DetachEvent;
   var sendRequest = require('sendRequest').sendRequest;
   var utils = require('utils');
   var validate = require('schemaUtils').validate;
@@ skipping 121 matching lines @@
       throw new Error("Massager already registered for event: " + name);
     eventArgumentMassagers[name] = fn;
   };
 
   // Dispatches a named event with the given JSON array, which is deserialized
   // before dispatch. The JSON array is the list of arguments that will be
   // sent with the event callback.
   chromeHidden.Event.dispatchJSON = function(name, args) {
     if (attachedNamedEvents[name]) {
       if (args) {
-        args = chromeHidden.JSON.parse(args);
+        // TODO(asargent): This is an antiquity. Until all callers of
+        // dispatchJSON use actual values, this must remain here to catch the
+        // cases where a caller has hard-coded a JSON string to pass in.
+        if (typeof(args) == "string") {
+          args = chromeHidden.JSON.parse(args);
+        }
         if (eventArgumentMassagers[name])
           eventArgumentMassagers[name](args);
       }
       var result = attachedNamedEvents[name].dispatch.apply(
           attachedNamedEvents[name], args);
       if (result && result.validationErrors)
         return result.validationErrors;
     }
   };
 
@@ skipping 207 matching lines @@
       if (event)
         event.detach_(false);
     }
   };
 
   chromeHidden.dispatchError = function(msg) {
     console.error(msg);
   };
 
   exports.Event = chrome.Event;