MediaSession API Not Supported in Android WebView with flutter_inappwebview

[T04N]

The navigator.mediaSession API is not supported in Android WebView when using the flutter_inappwebview package, resulting in undefined for navigator.mediaSession and an empty navigator object (JSON.stringify(navigator) = {}). This prevents media notification controls (play, pause, seek) from working on Android, while the same code works fine on iOS (WKWebView).

Steps to Reproduce

Use flutter_inappwebview (version 6.0.0) to load a YouTube video iframe.

Configure InAppWebView with the following settings:
initialSettings: InAppWebViewSettings(
javaScriptEnabled: true,
mediaPlaybackRequiresUserGesture: false,
allowsInlineMediaPlayback: true,
allowBackgroundAudioPlaying: true,
userAgent: 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/139.0.0.0 Safari/537.36',
)

Inject JavaScript to check navigator.mediaSession:
await webViewController.evaluateJavascript(source: '''
console.log('[MediaSession] Navigator object:', JSON.stringify(navigator));
console.log('[MediaSession] MediaSession exists:', 'mediaSession' in navigator);
if ('mediaSession' in navigator) {
console.log('[MediaSession] MediaSession API supported');
} else {
console.error('[MediaSession] MediaSession API not supported');
}
''');

Run the app on an Android device (tested on Android 12, System WebView Chrome/139.0.7258.143).

Check logs via chrome://inspect.
Expected Behavior

navigator.mediaSession should be available in Android WebView, as it is in iOS WKWebView, to enable media notification controls.

JSON.stringify(navigator) should return a non-empty object with properties like userAgent, mediaSession, etc.

Actual Behavior

Logs show:

I/chromium: [INFO:CONSOLE:1] "[MediaSession] Navigator object: {}"
I/chromium: [INFO:CONSOLE:2] "[MediaSession] MediaSession exists: false"
I/chromium: [INFO:CONSOLE:3] "[MediaSession] MediaSession API not supported"

navigator.mediaSession is undefined, and navigator object is empty, preventing media notification controls.

Environment

Flutter Version: 3.x.x
flutter_inappwebview Version: 6.0.0
Platform: Android (tested on Android 12, Samsung Galaxy S10+)
System WebView: Chrome/139.0.7258.143

User Agent: Mozilla/5.0 (Linux; Android 12; SM-G975F Build/SP1A.210812.016; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/139.0.7258.143 Mobile Safari/537.36

iOS Behavior: Works correctly with WKWebView.

Additional Context

The custom userAgent set in InAppWebViewSettings is not applied; Android WebView uses the default device User Agent with wv.

According to MDN, navigator.mediaSession is not supported in Android WebView, but works in iOS WKWebView (https://developer.mozilla.org/en-US/docs/Web/API/MediaSession).
Related W3C issue: w3c/mediasession#337

Is there a way to enable navigator.mediaSession in Android WebView, or is this a known limitation? Any workarounds?

Logs

I/chromium(21084): [INFO:CONSOLE:1] "[MediaSession] User Agent: Mozilla/5.0 (Linux; Android 12; SM-G975F Build/SP1A.210812.016; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/139.0.7258.143 Mobile Safari/537.36"
I/chromium(21084): [INFO:CONSOLE:2] "[MediaSession] Navigator object: {}"
I/chromium(21084): [INFO:CONSOLE:3] "[MediaSession] MediaSession API not supported"

Request
Can flutter_inappwebview enable navigator.mediaSession in Android WebView?

If not supported, are there recommended workarounds (e.g., native MediaSession integration via platform channels)?