Release Extractors when ExtractorSampleSource is released.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=126691912

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

@@ -111,8 +111,8 @@ public final class ExtractorSampleSource implements SampleSource, ExtractorOutpu
   private final EventListener eventListener;
   private final DataSource dataSource;
   private final ConditionVariable loadCondition;
-  private final Loader loader;
   private final ExtractorHolder extractorHolder;
+  private final Loader loader;
 
   private Callback callback;
   private Allocator allocator;
@@ -171,8 +171,8 @@ public final class ExtractorSampleSource implements SampleSource, ExtractorOutpu
     this.eventHandler = eventHandler;
     dataSource = dataSourceFactory.createDataSource(bandwidthMeter);
     loadCondition = new ConditionVariable();
-    loader = new Loader("Loader:ExtractorSampleSource");
     extractorHolder = new ExtractorHolder(extractorsFactory.createExtractors(), this);
+    loader = new Loader("Loader:ExtractorSampleSource", extractorHolder);
     pendingResetPositionUs = C.UNSET_TIME_US;
     sampleQueues = new DefaultTrackOutput[0];
     length = C.LENGTH_UNBOUNDED;
@@ -640,7 +640,7 @@ public final class ExtractorSampleSource implements SampleSource, ExtractorOutpu
   /**
    * Stores a list of extractors and a selected extractor when the format has been detected.
    */
-  private static final class ExtractorHolder {
+  private static final class ExtractorHolder implements Loader.Releasable {
 
     private final Extractor[] extractors;
     private final ExtractorOutput extractorOutput;
@@ -691,6 +691,14 @@ public final class ExtractorSampleSource implements SampleSource, ExtractorOutpu
       return extractor;
     }
 
+    @Override
+    public void release() {
+      if (extractor != null) {
+        extractor.release();
+        extractor = null;
+      }
+    }
+
   }
 
 }

library/src/main/java/com/google/android/exoplayer/upstream/Loader.java

@@ -73,6 +73,18 @@ public final class Loader {
   }
 
   /**
+   * An object that can be released on the loading thread when {@link Loader#release()} is called.
+   */
+  public interface Releasable {
+
+    /**
+     * Releases any resources associated with the instance.
+     */
+    void release();
+
+  }
+
+  /**
    * A callback to be notified of {@link Loader} events.
    */
   public interface Callback<T extends Loadable> {
@@ -135,6 +147,7 @@ public final class Loader {
   private static final int MSG_FATAL_ERROR = 4;
 
   private final ExecutorService downloadExecutorService;
+  private final Releasable releasable;
 
   private LoadTask<? extends Loadable> currentTask;
   private IOException fatalError;
@@ -143,7 +156,17 @@ public final class Loader {
    * @param threadName A name for the loader's thread.
    */
   public Loader(String threadName) {
+    this(threadName, null);
+  }
+
+  /**
+   * @param threadName A name for the loader's thread.
+   * @param releasable An object to release on the loader's thread when {@link Loader#release()} is
+   *     called.
+   */
+  public Loader(String threadName, Releasable releasable) {
     this.downloadExecutorService = Util.newSingleThreadExecutor(threadName);
+    this.releasable = releasable;
   }
 
   /**
@@ -223,6 +246,14 @@ public final class Loader {
     if (currentTask != null) {
       currentTask.cancel(true);
     }
+    if (releasable != null) {
+      downloadExecutorService.submit(new Runnable() {
+        @Override
+        public void run() {
+          releasable.release();
+        }
+      });
+    }
     downloadExecutorService.shutdown();
   }