Remove unused method.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=117338990

library/src/main/java/com/google/android/exoplayer/FrameworkSampleSource.java

@@ -146,11 +146,6 @@ public final class FrameworkSampleSource implements SampleSource {
     return true;
   }
 
-  @Override
-  public boolean isPrepared() {
-    return prepared;
-  }
-
   @Override
   public long getDurationUs() {
     return C.UNKNOWN_TIME_US;

library/src/main/java/com/google/android/exoplayer/MultiSampleSource.java

@@ -36,16 +36,16 @@ public class MultiSampleSource implements SampleSource {
 
   @Override
   public boolean prepare(long positionUs) throws IOException {
-    if (this.prepared) {
+    if (prepared) {
       return true;
     }
-    boolean prepared = true;
+    boolean sourcesPrepared = true;
     for (int i = 0; i < sources.length; i++) {
-      prepared &= sources[i].prepare(positionUs);
+      sourcesPrepared &= sources[i].prepare(positionUs);
     }
-    if (prepared) {
-      this.prepared = true;
-      this.durationUs = C.UNKNOWN_TIME_US;
+    if (sourcesPrepared) {
+      prepared = true;
+      durationUs = C.UNKNOWN_TIME_US;
       int totalTrackGroupCount = 0;
       for (int i = 0; i < sources.length; i++) {
         totalTrackGroupCount += sources[i].getTrackGroups().length;
@@ -66,11 +66,6 @@ public class MultiSampleSource implements SampleSource {
     return prepared;
   }
 
-  @Override
-  public boolean isPrepared() {
-    return prepared;
-  }
-
   @Override
   public TrackGroupArray getTrackGroups() {
     return trackGroups;

library/src/main/java/com/google/android/exoplayer/SampleSource.java

@@ -34,13 +34,6 @@ public interface SampleSource {
    */
   boolean prepare(long positionUs) throws IOException;
 
-  /**
-   * Returns whether the source is prepared.
-   *
-   * @return True if the source is prepared. False otherwise.
-   */
-  boolean isPrepared();
-
   /**
    * Returns the duration of the source.
    * <p>
@@ -58,7 +51,7 @@ public interface SampleSource {
    *
    * @return The {@link TrackGroup}s.
    */
-  public TrackGroupArray getTrackGroups();
+  TrackGroupArray getTrackGroups();
 
   /**
    * Indicates to the source that it should continue buffering data for its enabled tracks.
@@ -103,7 +96,7 @@ public interface SampleSource {
    * @param positionUs The current playback position in microseconds.
    * @return A {@link TrackStream} from which the enabled track's data can be read.
    */
-  public TrackStream enable(TrackSelection selection, long positionUs);
+  TrackStream enable(TrackSelection selection, long positionUs);
 
   /**
    * Releases the source.

library/src/main/java/com/google/android/exoplayer/SingleSampleSource.java

@@ -95,11 +95,6 @@ public final class SingleSampleSource implements SampleSource, TrackStream, Load
     return true;
   }
 
-  @Override
-  public boolean isPrepared() {
-    return loader != null;
-  }
-
   @Override
   public long getDurationUs() {
     return durationUs;

library/src/main/java/com/google/android/exoplayer/chunk/ChunkSampleSource.java

@@ -167,11 +167,6 @@ public class ChunkSampleSource implements SampleSource, TrackStream, Loader.Call
     return true;
   }
 
-  @Override
-  public boolean isPrepared() {
-    return state != STATE_IDLE;
-  }
-
   @Override
   public long getDurationUs() {
     return durationUs;

library/src/main/java/com/google/android/exoplayer/extractor/ExtractorSampleSource.java

@@ -351,11 +351,6 @@ public final class ExtractorSampleSource implements SampleSource, ExtractorOutpu
     return false;
   }
 
-  @Override
-  public boolean isPrepared() {
-    return prepared;
-  }
-
   @Override
   public long getDurationUs() {
     return durationUs;

library/src/main/java/com/google/android/exoplayer/hls/HlsSampleSource.java

@@ -176,11 +176,6 @@ public final class HlsSampleSource implements SampleSource, Loader.Callback {
     return false;
   }
 
-  @Override
-  public boolean isPrepared() {
-    return prepared;
-  }
-
   @Override
   public long getDurationUs() {
     return chunkSource.getDurationUs();