[document pip] Add manual wpt test for hiding return to opener button

This CL adds a manual wpt test to check that the
`disallowReturnToOpener` parameter to the document picture-in-picture
api works as expected.

Bug: 310971727
Change-Id: I19c43442f714b8cfce46e2e4bedbb4a2cf46ae3e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5375045
Commit-Queue: Tommy Steimel <steimel@chromium.org>
Reviewed-by: Frank Liberato <liberato@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1273544}
diff --git a/document-picture-in-picture/hide-return-to-opener-button-manual.https.html b/document-picture-in-picture/hide-return-to-opener-button-manual.https.html
new file mode 100644
index 0000000..17cd665
--- /dev/null
+++ b/document-picture-in-picture/hide-return-to-opener-button-manual.https.html
@@ -0,0 +1,21 @@
+<!DOCTYPE html>
+<title>Test that using documentPictureInPicture's disallowReturnToOpener
+  parameter hides the return to opener button</title>
+<body>
+  <p>
+  This tests that a document picture-in-picture window opened with the `disallowReturnToOpener`
+  parameter set to `true` does not display a button to return to the opener.
+    <ol>
+      <li>Click on the "Open document picture-in-picture window" button below.</li>
+      <li>Check that it does not display that button.</li>
+    </ol>
+  </p>
+  <input type="button" id="btnOpenPip" value="Open document picture-in-picture window" />
+<script>
+const btnOpenPip = document.getElementById('btnOpenPip');
+btnOpenPip.addEventListener('click', async () => {
+  const pipWindow = await documentPictureInPicture.requestWindow({ disallowReturnToOpener: true });
+  pipWindow.document.body.innerText = 'This document picture-in-picture window should not display a button to return to the opener';
+});
+</script>
+</body>