[Picture-in-Picture] Add test for consuming user gesture.

This merge all request Picture-in-Picture tests into one test file and
adds one test to make sure user gesture is consumed by request
Picture-in-Picture so that a site couldn't produce a popup and a video
played in Picture-in-Picture on the same gesture.

Bug: 806249
Change-Id: Id974342b5cb48c1b60a44074d41603e93d2192e7
Reviewed-on: https://chromium-review.googlesource.com/909148
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Reviewed-by: apacible <apacible@chromium.org>
Commit-Queue: Mounir Lamouri <mlamouri@chromium.org>
Cr-Commit-Position: refs/heads/master@{#535694}

picture-in-picture/request-picture-in-picture.html

@@ -9,5 +9,21 @@
 <script>
 promise_test(t => {
   return requestPictureInPictureWithTrustedClick(document.createElement('video'));
-});
+}, 'request Picture-in-Picture resolves on user click');
+
+promise_test(t => {
+  return promise_rejects(t, 'NotAllowedError',
+      document.createElement('video').requestPictureInPicture());
+}, 'request Picture-in-Picture requires a user gesture');
+
+promise_test(t => {
+  return callWithTrustedClick(() => {
+    const first = document.createElement('video').requestPictureInPicture();
+    const second = document.createElement('video').requestPictureInPicture();
+    return Promise.all([
+      first,
+      promise_rejects(t, 'NotAllowedError', second)
+    ]);
+  });
+}, 'request Picture-in-Picture consumes user gesture');
 </script>