Add sanbdoxed_pages to allow extension/app pages to be served in a sandboxed, unique origin

chrome/test/data/extensions/api_test/sandboxed_pages/sandboxed.html

Index: chrome/test/data/extensions/api_test/sandboxed_pages/sandboxed.html
diff --git a/chrome/test/data/extensions/api_test/sandboxed_pages/sandboxed.html b/chrome/test/data/extensions/api_test/sandboxed_pages/sandboxed.html
new file mode 100644
index 0000000000000000000000000000000000000000..78e79c1a121f7cf5714a5b7673f4810ea40eebaa
--- /dev/null
+++ b/chrome/test/data/extensions/api_test/sandboxed_pages/sandboxed.html
@@ -0,0 +1,16 @@
+This page should be sandboxed.
+
+<script>
+// We're not served with the extension default CSP, we can use inline script.
+onload = function() {
+  var secret = 'sandboxed_window_secret';
+
+  if (chrome.extension) {
+    chrome.test.notifyFail('Extension APIs should not be injected.');
+    return;
+  }
+
+  var mainWindow = window.opener || window.top;
+  mainWindow.postMessage(mainWindow.secret, '*');
+};
+</script>