Only return the casting button when there are devices to cast to.

[dero]

Summary

Only resolve the cast button promise when cast receiver devices are detected.

Fixes #179

[beaufortfrancois]

The casting button would not be removed when cast devices are not available anymore sadly.

I believe we should have a displayCastState() function that would simply toggle cast button visibility when CAST_STATE_CHANGED event is fired. WDYT?

[dero]

@beaufortfrancois Right. I wasn't sure if dynamically removing the cast button from the once established UI without indicating what's happened would be a good solution from the UX perspective.

But I guess with casting it's a relatively common pattern for the button to only appear when cast targets are available.

Updated in 7cdfcdd. Would that work?

[beaufortfrancois]

This line is not needed as castButton will only be added to the document once promise is resolved right?

[dero]

@beaufortfrancois The button is added to the document as soon as the Google Cast API becomes available after the recent changes – regardless of whether cast devices are available or not.

The button visibility (controlled using the class name) then depends on cast state changes.

[beaufortfrancois]

My understanding is that applyCastState() is called just before resolve(castButton). As applyCastState() controls the button visibility, the fist castButton.classList.add(CAST_BUTTON_HIDDEN_CLASSNAME); would not shown to the user.

[dero]

Quite right. 🤦‍♂️

Thank you. Removed in 3cc1ef6.

[beaufortfrancois]

Thank you for working on this!

[felipebochehin87]

Looks good to me. Cast button is not displayed when there are no devices to cast to.