Add support for deferring app initialization when testing.

remoting/webapp/crd/html/template_main.html

Index: remoting/webapp/crd/html/template_main.html
diff --git a/remoting/webapp/crd/html/template_main.html b/remoting/webapp/crd/html/template_main.html
index 3abdc6ff0aba3d803bda48aecf18731cff625d34..70facda00c2c6c31e5f20f98df849777408e4c4b 100644
--- a/remoting/webapp/crd/html/template_main.html
+++ b/remoting/webapp/crd/html/template_main.html
@@ -33,6 +33,15 @@ found in the LICENSE file.
            hidden, but are shown appropriately when the mode changes. -->
       <section id="loading-mode" data-ui-mode="">
         <em>Loading&hellip;</em>
+        <div id="browser-test-deferred-init" hidden>
+        <p>
+          Running in test mode. If you are seeing this message in any other
+          context, please <a href="http://crbug.com" target="_blank">file a
+          bug</a>.
+        </p>
+        <p>
+          <button id="browser-test-continue-init">Continue</button>
+        </p>
       </section>
 
       <div id="daemon-plugin-container"></div>