Fix miscellaneous nits

PiperOrigin-RevId: 326208366

library/core/src/main/java/com/google/android/exoplayer2/source/DefaultMediaSourceFactory.java

@@ -379,6 +379,7 @@ public final class DefaultMediaSourceFactory implements MediaSourceFactory {
               + " media items with an ad tag uri.");
       return mediaSource;
     }
+    @Nullable
     AdsLoader adsLoader = adSupportProvider.getAdsLoader(mediaItem.playbackProperties.adTagUri);
     if (adsLoader == null) {
       Log.w(TAG, "Playing media without ads. No AdsLoader for provided adTagUri");

library/core/src/test/java/com/google/android/exoplayer2/audio/DefaultAudioSinkTest.java

@@ -33,18 +33,7 @@ import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.robolectric.annotation.Config;
 
-/**
+/** Unit tests for {@link DefaultAudioSink}. */
- * Unit tests for {@link DefaultAudioSink}.
- *
- * <p>Note: the Robolectric-provided AudioTrack instantiated in the audio sink uses only the Java
- * part of AudioTrack with a {@code ShadowPlayerBase} underneath. This means it will not consume
- * data (i.e., the {@link android.media.AudioTrack#write} methods just return 0), so these tests are
- * currently limited to verifying behavior that doesn't rely on consuming data, and the position
- * will stay at its initial value. For example, we can't verify {@link
- * AudioSink#handleBuffer(ByteBuffer, long, int)} handling a complete buffer, or queueing audio then
- * draining to the end of the stream. This could be worked around by having a test-only mode where
- * {@link DefaultAudioSink} automatically treats audio as consumed.
- */
 @RunWith(AndroidJUnit4.class)
 public final class DefaultAudioSinkTest {
 

library/extractor/src/main/java/com/google/android/exoplayer2/extractor/mp4/AtomParsers.java

@@ -1260,8 +1260,7 @@ import org.checkerframework.checker.nullness.compatqual.NullableType;
           if (initializationDataBytes != null) {
             if (MimeTypes.AUDIO_AAC.equals(mimeType)) {
               // Update sampleRate and channelCount from the AudioSpecificConfig initialization
-              // data,
+              // data, which is more reliable. See [Internal: b/10903778].
-              // which is more reliable. See [Internal: b/10903778].
               AacUtil.Config aacConfig = AacUtil.parseAudioSpecificConfig(initializationDataBytes);
               sampleRate = aacConfig.sampleRateHz;
               channelCount = aacConfig.channelCount;