browser-plugin: Send a JSON string for the detail data with the events.

chrome/renderer/resources/extensions/web_view.js

Index: chrome/renderer/resources/extensions/web_view.js
diff --git a/chrome/renderer/resources/extensions/web_view.js b/chrome/renderer/resources/extensions/web_view.js
index 65582f2fa6471e2c774f68d77168d3b6c89b9c3f..fcfbe1345528630d40d6dcd6e4e75bc3e287bcf3 100644
--- a/chrome/renderer/resources/extensions/web_view.js
+++ b/chrome/renderer/resources/extensions/web_view.js
@@ -157,8 +157,9 @@ WebView.prototype.setupEvent_ = function(eventname, attribs) {
   var node = this.node_;
   this.objectNode_.addEventListener('-internal-' + eventname, function(e) {
     var evt = new Event(eventname);
+    var detail = e.detail ? JSON.parse(e.detail) : {};
     attribs.forEach(function(attribname) {
-      evt[attribname] = e.detail[attribname];
+      evt[attribname] = detail[attribname];
     });
     node.dispatchEvent(evt);
   });