[Picture-in-Picture] Add a layout test for detached frame.

This CL adds a test to make sure requesting Picture-in-Picture rejects
when frame is detached.

Bug: 806249
Change-Id: I2f9a029cc03fa8977400f908c87f80ed69674e93
Reviewed-on: https://chromium-review.googlesource.com/1065732
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Commit-Queue: François Beaufort <beaufort.francois@gmail.com>
Cr-Commit-Position: refs/heads/master@{#560605}

picture-in-picture/resources/picture-in-picture-helpers.js

@@ -14,18 +14,22 @@ function callWithTrustedClick(callback) {
   });
 }
 
-function loadVideo() {
-  return new Promise(resolve => {
-    let video = document.createElement('video');
-    video.src = '/media/movie_5.ogv';
+function loadVideo(activeDocument, sourceUrl) {
+  return new Promise((resolve, reject) => {
+    const document = activeDocument || window.document;
+    const video = document.createElement('video');
+    video.src = sourceUrl || '/media/movie_5.ogv';
     video.onloadedmetadata = () => {
       resolve(video);
     };
+    video.onerror = error => {
+      reject(error);
+    };
   });
 }
 
 // Calls requestPictureInPicture() in a context that's 'allowed to request PiP'.
 function requestPictureInPictureWithTrustedClick(videoElement) {
   return callWithTrustedClick(
       () => videoElement.requestPictureInPicture());
-}
+}