Run shim's watchForTag on document.DOMContentLoaded

chrome/renderer/resources/extensions/app_window_custom_bindings.js

Index: chrome/renderer/resources/extensions/app_window_custom_bindings.js
diff --git a/chrome/renderer/resources/extensions/app_window_custom_bindings.js b/chrome/renderer/resources/extensions/app_window_custom_bindings.js
index ed0edd1c299770ba99463eb174059bc9eafa0dc1..5d01ff582b1c6fc858b458209623d7e3e3f66049 100644
--- a/chrome/renderer/resources/extensions/app_window_custom_bindings.js
+++ b/chrome/renderer/resources/extensions/app_window_custom_bindings.js
@@ -5,6 +5,7 @@
 // Custom binding for the app_window API.
 
 var appWindowNatives = requireNative('app_window_natives');
+var renderViewObserverNatives = requireNative('renderViewObserverNatives');
 var Binding = require('binding').Binding;
 var Event = require('event_bindings').Event;
 var forEach = require('utils').forEach;
@@ -56,14 +57,15 @@ appWindow.registerCustomHook(function(bindingsAPI) {
         return;
       }
 
-      var willCallback = appWindowNatives.OnContextReady(windowParams.viewId,
-                                                         function(success) {
-        if (success) {
-          callback(view.chrome.app.window.current());
-        } else {
-          callback(undefined);
-        }
-      });
+      var willCallback =
+            renderViewObserverNatives.OnDocumentCreated(windowParams.viewId,
+                                                        function(success) {
+              if (success) {
+                callback(view.chrome.app.window.current());
+              } else {
+                callback(undefined);
+              }
+            });
       if (!willCallback) {
         callback(undefined);
       }