Android-based Chromecast devices error out on MediaCapabilities#decodingInfo().

[JulianDomingo]

Have you read the FAQ and checked for duplicate open issues?
Yes, #3818 relates to the same API, but not for issues on Chromecast.

What version of Shaka Player are you using?
v4.2.2. All latest release branches exhibit the same behavior where MediaCapabilities#decodingInfo is included in Shaka's variant filtering logic.

Can you reproduce the issue with our latest release version?
Yes (see above).

Can you reproduce the issue with the latest code from main?
Yes (see above).

Are you using the demo app or your own custom app?
Custom app (Cast receiver application), but demo app is inapplicable for Chromecast devices.

If custom app, can you reproduce the issue using our demo app?
No, but only because native Chrome browser does not implement MediaCapabilities#decodingInfo() the same way as the Chromecast platform.

What browser and OS are you using?
Chrome, CastOS.

For embedded devices (smart TVs, etc.), what model and firmware version are you using?
Chromecast with Google TV, Google Nest Hub

What are the manifest and license server URIs?
Any TS-based HLS playlist will work, e.g., https://test-streams.mux.dev/x36xhzz/x36xhzz.m3u8.

What configuration are you using? What is the output of player.getConfiguration()?
Default player configuration.

What did you do?
Simply load the sample manifest above on a Cast receiver application. Most Cast developers today use https://casttool.appspot.com/cactool/ for debugging. Go to chrome://inpsect and open the dev console for the Cast receiver session process, and observe the following error thrown:

shaka-player.compiled.debug.js:290 MediaCapabilities.decodingInfo() failed. {
   "type":"media-source",
   "audio":{
      "contentType":"video/mp2t; codecs=\"mp4a.40.2\"",
      "channels":2,
      "bitrate":8247438,
      "samplerate":1,
      "spatialRendering":false
   },
   "video":{
      "contentType":"video/mp2t; codecs=\"avc1.42E01E\"",
      "width":1920,
      "height":800,
      "bitrate":8247438,
      "framerate":1
   }
}
TypeError: Failed to execute 'decodingInfo' on 'MediaCapabilities': The audio configuration dictionary is not valid.
    at $jscomp.generator.Engine_.program_ 

What did you expect to happen?
Content loading should execute error-free.

What actually happened?
Player LOAD fails and throws the MediaCapabilities#decodingInfo() error above. As you can see, the error is due to the Chromecast platform not respecting the MIME type video/mp2t for the audio configuration object passed to MediaCapabilities#decodingInfo().

Technically, W3C specs indicate a valid audio configuration CANNOT contain a video/ prefix (see https://w3c.github.io/media-capabilities/#dictdef-audioconfiguration => https://w3c.github.io/media-capabilities/#valid-audio-mime-type). However, it seems browsers today make an exception to this rule for TS-based media.

[JulianDomingo]

A trivial solution is to always enable MCap polyfills for Android-based Cast devices, too.