Responsive Videos: avoid notice when param is not given.

[jeherve]

Fixes #3048

Changes proposed in this Pull Request:

Avoid PHP notice when param is not given.

This was already fixed in #3243, but got reverted by mistake in ab7f2e0

Testing instructions:

1. Add the following to your theme's functions.php file or to a functionality plugin:

function jeherve_enable_resp() {
       	add_theme_support( 'jetpack-responsive-videos' );
}
add_action( 'after_setup_theme', 'jeherve_enable_resp' );

2. Add a few videos from YouTube or Vimeo to your posts.
3. View your site on a mobile device.
4. Make sure you do not see any PHP notices.

Proposed changelog entry for your changes:

Responsive Videos: avoid PHP notice.

[matticbot]

Caution: This PR has changes that must be merged to WordPress.com
Please review this diff before merging: D17995-code. (newly created revision)

[jetpackbot]

That's a great PR description, thank you so much for your effort!

Generated by 🚫 dangerJS

[mdawaffe]

I don't see any PHP Notices even without the patch. What am I doing wrong?

Theme: 2017

[jeherve]

It seems to only happen with some specific themes. The last user report was from a user using a Premium theme, so I could not download it to test either. :(

I assume that some themes call the jetpack_responsive_videos_maybe_wrap_oembed function directly without passing it that second parameter.

[oskosk]

I can't reproduce the warning with the provided steps :( Found that a theme like slik-lite should be useful for testing cause there are a few sites in the wild using this theme and showing the warning right now.

[jeherve]

It looks like that theme includes a full copy fo the Responsive Videos tool:
https://themes.svn.wordpress.org/silk-lite/1.2.8/inc/jetpack/responsive-videos.php

[brbrr]

I wasn't able to reproduce it either :(

[oskosk]

Just realized that this PR is introducing something that was already there. I'm merging it.

[oskosk]

LGTM given that this piece of code was already supposed to be like this