Add check for null token when updating state

MediaController requires a non-null token as input, which updateState
did not check before calling. The token is required to be non-null
already for active media, but it can be null for resume players, so it's
possible for users to hit a race condition between the notification
removal (token set to null) and a final PlaybackState update (attempting
to use the token).

Also added an annotation to the MediaControllerFactory method so that Kotlin
code is aware of this requirement.

Fixes: 231733532
Test: atest MediaDataManagerTest
Change-Id: Id5e4a52cba74fafa04331a663cd4ce870fe920a2

packages/SystemUI/src/com/android/systemui/media/MediaControllerFactory.java

@@ -16,6 +16,7 @@
 
 package com.android.systemui.media;
 
+import android.annotation.NonNull;
 import android.content.Context;
 import android.media.session.MediaController;
 import android.media.session.MediaSession;
@@ -39,7 +40,7 @@ public class MediaControllerFactory {
      *
      * @param token The token for the session. This value must never be null.
      */
-    public MediaController create(MediaSession.Token token) {
+    public MediaController create(@NonNull MediaSession.Token token) {
         return new MediaController(mContext, token);
     }
 }

packages/SystemUI/src/com/android/systemui/media/MediaDataManager.kt

@@ -509,6 +509,11 @@ class MediaDataManager(
      */
     private fun updateState(key: String, state: PlaybackState) {
         mediaEntries.get(key)?.let {
+            val token = it.token
+            if (token == null) {
+                if (DEBUG) Log.d(TAG, "State updated, but token was null")
+                return
+            }
             val actions = createActionsFromState(it.packageName,
                     mediaControllerFactory.create(it.token), UserHandle(it.userId))
             val data = it.copy(

packages/SystemUI/src/com/android/systemui/media/MediaTimeoutListener.kt

@@ -161,8 +161,9 @@ class MediaTimeoutListener @Inject constructor(
                 destroyed = false
                 mediaController?.unregisterCallback(this)
                 field = value
-                mediaController = if (field.token != null) {
-                    mediaControllerFactory.create(field.token)
+                val token = field.token
+                mediaController = if (token != null) {
+                    mediaControllerFactory.create(token)
                 } else {
                     null
                 }

packages/SystemUI/tests/src/com/android/systemui/media/MediaDataManagerTest.kt

@@ -978,6 +978,26 @@ class MediaDataManagerTest : SysuiTestCase() {
                 anyBoolean())
     }
 
+    @Test
+    fun testPlaybackStateChange_keyHasNullToken_doesNothing() {
+        // When we get an update that sets the data's token to null
+        whenever(controller.metadata).thenReturn(metadataBuilder.build())
+        addNotificationAndLoad()
+        val data = mediaDataCaptor.value
+        assertThat(data.resumption).isFalse()
+        mediaDataManager.onMediaDataLoaded(KEY, null, data.copy(token = null))
+
+        // And then get a state update
+        val state = PlaybackState.Builder().build()
+        val callbackCaptor = argumentCaptor<(String, PlaybackState) -> Unit>()
+        verify(mediaTimeoutListener).stateCallback = capture(callbackCaptor)
+
+        // Then no changes are made
+        callbackCaptor.value.invoke(KEY, state)
+        verify(listener, never()).onMediaDataLoaded(eq(KEY), any(), any(), anyBoolean(), anyInt(),
+            anyBoolean())
+    }
+
     /**
      * Helper function to add a media notification and capture the resulting MediaData
      */