Don't kill Chrome Apps that make XHRs from guests.

chrome/test/data/extensions/platform_apps/web_view/content_script_fetch/content_script.js

Index: chrome/test/data/extensions/platform_apps/web_view/content_script_fetch/content_script.js
diff --git a/chrome/test/data/extensions/platform_apps/web_view/content_script_fetch/content_script.js b/chrome/test/data/extensions/platform_apps/web_view/content_script_fetch/content_script.js
new file mode 100644
index 0000000000000000000000000000000000000000..b5258cbc8fadabf63f3239d55d29b267ca442e38
--- /dev/null
+++ b/chrome/test/data/extensions/platform_apps/web_view/content_script_fetch/content_script.js
@@ -0,0 +1,30 @@
+// Copyright 2017 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 embedder = null;
+
+function reportResult(result) {
+  var msg = ['fetch-' + result];
+  embedder.postMessage(JSON.stringify(msg), '*');
+}
+
+window.addEventListener('message', function(e) {
+  embedder = e.source;
+  var data = JSON.parse(e.data);
+  if (data[0] == 'start-fetch') {
+    fetch('http://127.0.0.1:' + location.port + '/extensions/xhr.txt')
+        .then((result) => result.text())
+        .then((text) => {
+          reportResult(
+              (text == 'File to request via XHR.\n') ? 'success' : 'failure');
+        })
+        .catch(err => {
+          reportResult('failure');
+        });
+  } else {
+    reportResult('unexpected-message');
+  }
+});
+
+window.console.log('Script has been successfully injected.');