Pass the RenderProcessHost id on retargeting.

chrome/test/data/extensions/api_test/webnavigation/userAction/a.js

Index: chrome/test/data/extensions/api_test/webnavigation/userAction/a.js
diff --git a/chrome/test/data/extensions/api_test/webnavigation/userAction/a.js b/chrome/test/data/extensions/api_test/webnavigation/userAction/a.js
new file mode 100644
index 0000000000000000000000000000000000000000..1b83105448d76cf0732ebb242a99ca68361bcd54
--- /dev/null
+++ b/chrome/test/data/extensions/api_test/webnavigation/userAction/a.js
@@ -0,0 +1,7 @@
+// Copyright 2016 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 port = location.search.slice(1);
+var f = document.getElementById('subframe');
+f.src = 'http://127.0.0.1:' + port + '/extensions/api_test/webnavigation/userAction/subframe.html';