APContainer: fix AP not showing after screen off

When playing a video with "Play in background" enabled, if the screen is
switched off, the player will switch to audio, triggering a
ACTION_SHOW_PLAYER scheduled with a 100L delay that has been there since
java.
Because the screen is switched off, onPause is called, triggering a
cancellation of ACTION_SHOW_PLAYER in the LifecyleAwareScheduler,
before it can execute it.
To ensure ACTION_SHOW_PLAYER is executed when switching the screen
back on, a flag is set and checked in onResume to call
showAudioPlayerImpl

application/vlc-android/src/org/videolan/vlc/gui/AudioPlayerContainerActivity.kt

@@ -105,6 +105,7 @@ open class AudioPlayerContainerActivity : BaseActivity(), KeycodeListener, Sched
     private var scanProgressBar: ProgressBar? = null
     private lateinit var resumeCard: Snackbar
     private var preventRescan = false
+    private var showAudioPlayerWhenResumed = false
 
     private var playerShown = false
     val tipsDelegate: AudioTipsDelegate by lazy(LazyThreadSafetyMode.NONE) { AudioTipsDelegate(this) }
@@ -511,6 +512,8 @@ open class AudioPlayerContainerActivity : BaseActivity(), KeycodeListener, Sched
         else
             applyMarginToProgressBar(0)
         setContentBottomPadding()
+        if (showAudioPlayerWhenResumed)
+            showAudioPlayerImpl()
         super.onResume()
     }
 
@@ -588,10 +591,14 @@ open class AudioPlayerContainerActivity : BaseActivity(), KeycodeListener, Sched
     private fun showAudioPlayer() {
         if (isFinishing) return
         scheduler.scheduleAction(ACTION_SHOW_PLAYER, 100L)
+        // due to the 100L delay when scheduling ACTION_SHOW_PLAYER
+        // if switching screen off, it can be canceled, this ensures that onResume the player is shown
+        showAudioPlayerWhenResumed = true
     }
 
     private fun showAudioPlayerImpl() {
         if (isFinishing) return
+        showAudioPlayerWhenResumed = false
         if (!isAudioPlayerReady) initAudioPlayer()
         if (audioPlayerContainer.visibility != View.VISIBLE) {
             audioPlayerContainer.visibility = View.VISIBLE