Use PiP window size when abr.restrictToElementSize is true

[absidue]

Have you read the FAQ and checked for duplicate open issues?
Yes

Is your feature request related to a problem? Please describe.

The picture-in-picture window is usually a different size to the video element on the page, as most browsers default to a small PIP window. As shaka-player currently only looks at the size of the video element, it uses larger variants than needed when PIP is enabled.

Describe the solution you'd like

HTMLVideoElement#requestPictureInPicture returns a PictureInPictureWindow that contains the width and height of the picture-in-picture window as well as a resize event. shaka-player could forward the dimensions of the window and any changes to them from the PipButton component to the ABR manager, where it could be used for making decisions about which variant to use.

https://developer.mozilla.org/en-US/docs/Web/API/PictureInPictureWindow

Describe alternatives you've considered

Leaving as is. This feature request is about optimising resource usage, so if it isn't implemented it's not like there will be "missing" functionality.

Additional context

Are you planning to send a PR to add it?

As this would require changes to the ABR manager interface, it is probably best to leave it to the experts.

[avelad]

@absidue I created a PR to implement this --> #7880 Can you review it? Thanks!

[avelad]

@absidue #7882 :)

[absidue]

Looks great to me, thank you!!!