PiP 2.0: Reuse player when window is opened.

This CL fixes a bug introduced recently[1] so that the HTML media player
is now reused if the Document Picture-in-Picture API is enabled.

[1] https://chromium-review.googlesource.com/c/chromium/src/+/4190826

Change-Id: I24b7d0080cf9ee9e054c2a20a2f6d98911898b06
Bug: 1411201
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4202152
Reviewed-by: Yoav Weiss <yoavweiss@chromium.org>
Commit-Queue: Fr <beaufort.francois@gmail.com>
Cr-Commit-Position: refs/heads/main@{#1098495}

third_party/blink/renderer/core/html/media/html_media_element.cc

@@ -647,8 +647,12 @@ void HTMLMediaElement::DidMoveToNewDocument(Document& old_document) {
 
 bool HTMLMediaElement::ShouldReusePlayer(Document& old_document,
                                          Document& new_document) const {
+  // Don't reuse player if the Document Picture-in-Picture API is disabled for
+  // both documents.
   if (!RuntimeEnabledFeatures::DocumentPictureInPictureAPIEnabled(
-          GetExecutionContext())) {
+          old_document.domWindow()->GetExecutionContext()) &&
+      !RuntimeEnabledFeatures::DocumentPictureInPictureAPIEnabled(
+          new_document.domWindow()->GetExecutionContext())) {
     return false;
   }