Defer adsManager.init until the timeline has loaded

If the app seeks after we get an ads manager but before the player exposes the
timeline with ads, we would end up expecting to play a preroll even after the
seek request arrived. This caused the player to get stuck.

Wait until a non-empty timeline has been exposed via onTimelineChanged before
initializing IMA (at which point it can start polling the player position). Seek
requests are not handled while an ad is playing.

PiperOrigin-RevId: 265058325

extensions/ima/src/main/java/com/google/android/exoplayer2/ext/ima/ImaAdsLoader.java

@@ -338,6 +338,7 @@ public ImaAdsLoader buildForAdsResponse(String adsResponse) {
   private int lastVolumePercentage;
 
   private AdsManager adsManager;
+  private boolean initializedAdsManager;
   private AdLoadException pendingAdLoadError;
   private Timeline timeline;
   private long contentDurationMs;
@@ -613,8 +614,8 @@ public void start(EventListener eventListener, AdViewProvider adViewProvider) {
         adsManager.resume();
       }
     } else if (adsManager != null) {
-      // Ads have loaded but the ads manager is not initialized.
-      startAdPlayback();
+      adPlaybackState = new AdPlaybackState(getAdGroupTimesUs(adsManager.getAdCuePoints()));
+      updateAdPlaybackState();
     } else {
       // Ads haven't loaded yet, so request them.
       requestAds(adViewGroup);
@@ -688,7 +689,8 @@ public void onAdsManagerLoaded(AdsManagerLoadedEvent adsManagerLoadedEvent) {
     if (player != null) {
       // If a player is attached already, start playback immediately.
       try {
-        startAdPlayback();
+        adPlaybackState = new AdPlaybackState(getAdGroupTimesUs(adsManager.getAdCuePoints()));
+        updateAdPlaybackState();
       } catch (Exception e) {
         maybeNotifyInternalError("onAdsManagerLoaded", e);
       }
@@ -968,6 +970,10 @@ public void onTimelineChanged(
     if (contentDurationUs != C.TIME_UNSET) {
       adPlaybackState = adPlaybackState.withContentDurationUs(contentDurationUs);
     }
+    if (!initializedAdsManager && adsManager != null) {
+      initializedAdsManager = true;
+      initializeAdsManager();
+    }
     onPositionDiscontinuity(Player.DISCONTINUITY_REASON_INTERNAL);
   }
 
@@ -1041,7 +1047,7 @@ public void onPositionDiscontinuity(@Player.DiscontinuityReason int reason) {
 
   // Internal methods.
 
-  private void startAdPlayback() {
+  private void initializeAdsManager() {
     AdsRenderingSettings adsRenderingSettings = imaFactory.createAdsRenderingSettings();
     adsRenderingSettings.setEnablePreloading(ENABLE_PRELOADING);
     adsRenderingSettings.setMimeTypes(supportedMimeTypes);
@@ -1056,10 +1062,9 @@ private void startAdPlayback() {
       adsRenderingSettings.setUiElements(adUiElements);
     }
 
-    // Set up the ad playback state, skipping ads based on the start position as required.
+    // Skip ads based on the start position as required.
     long[] adGroupTimesUs = getAdGroupTimesUs(adsManager.getAdCuePoints());
-    adPlaybackState = new AdPlaybackState(adGroupTimesUs);
-    long contentPositionMs = player.getCurrentPosition();
+    long contentPositionMs = player.getContentPosition();
     int adGroupIndexForPosition =
         adPlaybackState.getAdGroupIndexForPositionUs(C.msToUs(contentPositionMs));
     if (adGroupIndexForPosition > 0 && adGroupIndexForPosition != C.INDEX_UNSET) {
@@ -1093,7 +1098,6 @@ private void startAdPlayback() {
       pendingContentPositionMs = contentPositionMs;
     }
 
-    // Start ad playback.
     adsManager.init(adsRenderingSettings);
     updateAdPlaybackState();
     if (DEBUG) {

extensions/ima/src/test/java/com/google/android/exoplayer2/ext/ima/ImaAdsLoaderTest.java

@@ -143,7 +143,8 @@ public void testStart_updatesAdPlaybackState() {
     assertThat(adsLoaderListener.adPlaybackState)
         .isEqualTo(
             new AdPlaybackState(/* adGroupTimesUs= */ 0)
-                .withAdDurationsUs(PREROLL_ADS_DURATIONS_US));
+                .withAdDurationsUs(PREROLL_ADS_DURATIONS_US)
+                .withContentDurationUs(CONTENT_DURATION_US));
   }
 
   @Test