chromium/third_party/blink/web_tests/virtual/document-picture-in-picture-user-activation/README.md

This suite runs some tests in `external/wpt/document-picture-in-picture/` with
`--enable-blink-features=DocumentPictureInPictureUserActivation`.

TODO(https://crbug.com/331246719): This should be removed when the feature flag
is removed.