Rename SingleTrackMetadataOutput ahead of real metadata support

Issue #2176

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=144969838

library/src/main/java/com/google/android/exoplayer2/source/chunk/ChunkExtractorWrapper.java

@@ -30,15 +30,15 @@ import java.io.IOException;
 /**
  * An {@link Extractor} wrapper for loading chunks containing a single track.
  * <p>
- * The wrapper allows switching of the {@link SingleTrackMetadataOutput} and {@link TrackOutput}
- * which receive parsed data.
+ * The wrapper allows switching of the {@link SeekMapOutput} and {@link TrackOutput} that receive
+ * parsed data.
  */
 public final class ChunkExtractorWrapper implements ExtractorOutput, TrackOutput {
 
   /**
-   * Receives metadata associated with the track as extracted by the wrapped {@link Extractor}.
+   * Receives {@link SeekMap}s extracted by the wrapped {@link Extractor}.
    */
-  public interface SingleTrackMetadataOutput {
+  public interface SeekMapOutput {
 
     /**
      * @see ExtractorOutput#seekMap(SeekMap)
@@ -53,7 +53,7 @@ public final class ChunkExtractorWrapper implements ExtractorOutput, TrackOutput
   private final boolean resendFormatOnInit;
 
   private boolean extractorInitialized;
-  private SingleTrackMetadataOutput metadataOutput;
+  private SeekMapOutput seekMapOutput;
   private TrackOutput trackOutput;
   private Format sentFormat;
 
@@ -68,7 +68,7 @@ public final class ChunkExtractorWrapper implements ExtractorOutput, TrackOutput
    * @param preferManifestDrmInitData Whether {@link DrmInitData} defined in {@code manifestFormat}
    *     should be preferred when the sample and manifest {@link Format}s are merged.
    * @param resendFormatOnInit Whether the extractor should resend the previous {@link Format} when
-   *     it is initialized via {@link #init(SingleTrackMetadataOutput, TrackOutput)}.
+   *     it is initialized via {@link #init(SeekMapOutput, TrackOutput)}.
    */
   public ChunkExtractorWrapper(Extractor extractor, Format manifestFormat,
       boolean preferManifestDrmInitData, boolean resendFormatOnInit) {
@@ -79,14 +79,14 @@ public final class ChunkExtractorWrapper implements ExtractorOutput, TrackOutput
   }
 
   /**
-   * Initializes the extractor to output to the provided {@link SingleTrackMetadataOutput} and
+   * Initializes the extractor to output to the provided {@link SeekMapOutput} and
    * {@link TrackOutput} instances, and configures it to receive data from a new chunk.
    *
-   * @param metadataOutput The {@link SingleTrackMetadataOutput} that will receive metadata.
+   * @param seekMapOutput The {@link SeekMapOutput} that will receive extracted {@link SeekMap}s.
    * @param trackOutput The {@link TrackOutput} that will receive sample data.
    */
-  public void init(SingleTrackMetadataOutput metadataOutput, TrackOutput trackOutput) {
-    this.metadataOutput = metadataOutput;
+  public void init(SeekMapOutput seekMapOutput, TrackOutput trackOutput) {
+    this.seekMapOutput = seekMapOutput;
     this.trackOutput = trackOutput;
     if (!extractorInitialized) {
       extractor.init(this);
@@ -130,7 +130,7 @@ public final class ChunkExtractorWrapper implements ExtractorOutput, TrackOutput
 
   @Override
   public void seekMap(SeekMap seekMap) {
-    metadataOutput.seekMap(seekMap);
+    seekMapOutput.seekMap(seekMap);
   }
 
   // TrackOutput implementation.

library/src/main/java/com/google/android/exoplayer2/source/chunk/ContainerMediaChunk.java

@@ -21,7 +21,7 @@ import com.google.android.exoplayer2.extractor.DefaultTrackOutput;
 import com.google.android.exoplayer2.extractor.Extractor;
 import com.google.android.exoplayer2.extractor.ExtractorInput;
 import com.google.android.exoplayer2.extractor.SeekMap;
-import com.google.android.exoplayer2.source.chunk.ChunkExtractorWrapper.SingleTrackMetadataOutput;
+import com.google.android.exoplayer2.source.chunk.ChunkExtractorWrapper.SeekMapOutput;
 import com.google.android.exoplayer2.upstream.DataSource;
 import com.google.android.exoplayer2.upstream.DataSpec;
 import com.google.android.exoplayer2.util.Util;
@@ -30,7 +30,7 @@ import java.io.IOException;
 /**
  * A {@link BaseMediaChunk} that uses an {@link Extractor} to decode sample data.
  */
-public class ContainerMediaChunk extends BaseMediaChunk implements SingleTrackMetadataOutput {
+public class ContainerMediaChunk extends BaseMediaChunk implements SeekMapOutput {
 
   private final int chunkCount;
   private final long sampleOffsetUs;
@@ -85,7 +85,7 @@ public class ContainerMediaChunk extends BaseMediaChunk implements SingleTrackMe
     return bytesLoaded;
   }
 
-  // SingleTrackMetadataOutput implementation.
+  // SeekMapOutput implementation.
 
   @Override
   public final void seekMap(SeekMap seekMap) {

library/src/main/java/com/google/android/exoplayer2/source/chunk/InitializationChunk.java

@@ -22,7 +22,7 @@ import com.google.android.exoplayer2.extractor.Extractor;
 import com.google.android.exoplayer2.extractor.ExtractorInput;
 import com.google.android.exoplayer2.extractor.SeekMap;
 import com.google.android.exoplayer2.extractor.TrackOutput;
-import com.google.android.exoplayer2.source.chunk.ChunkExtractorWrapper.SingleTrackMetadataOutput;
+import com.google.android.exoplayer2.source.chunk.ChunkExtractorWrapper.SeekMapOutput;
 import com.google.android.exoplayer2.upstream.DataSource;
 import com.google.android.exoplayer2.upstream.DataSpec;
 import com.google.android.exoplayer2.util.ParsableByteArray;
@@ -32,7 +32,7 @@ import java.io.IOException;
 /**
  * A {@link Chunk} that uses an {@link Extractor} to decode initialization data for single track.
  */
-public final class InitializationChunk extends Chunk implements SingleTrackMetadataOutput,
+public final class InitializationChunk extends Chunk implements SeekMapOutput,
     TrackOutput {
 
   private final ChunkExtractorWrapper extractorWrapper;
@@ -85,7 +85,7 @@ public final class InitializationChunk extends Chunk implements SingleTrackMetad
     return seekMap;
   }
 
-  // SingleTrackMetadataOutput implementation.
+  // SeekMapOutput implementation.
 
   @Override
   public void seekMap(SeekMap seekMap) {