Make ExtractorSampleSource amenable to proguarding.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=122085277

demo/src/main/java/com/google/android/exoplayer/demo/PlayerActivity.java

@@ -283,8 +283,8 @@ public class PlayerActivity extends Activity implements SurfaceHolder.Callback,
       case Util.TYPE_OTHER:
         Allocator allocator = new DefaultAllocator(C.DEFAULT_BUFFER_SEGMENT_SIZE);
         DataSource dataSource = dataSourceFactory.createDataSource(player.getBandwidthMeter());
-        return new ExtractorSampleSource(uri, dataSource, allocator,
+        return new ExtractorSampleSource(uri, dataSource, allocator, C.DEFAULT_MUXED_BUFFER_SIZE,
-            C.DEFAULT_MUXED_BUFFER_SIZE, player.getMainHandler(), player, 0);
+            player.getMainHandler(), player, 0, ExtractorSampleSource.newDefaultExtractors());
       default:
         throw new IllegalStateException("Unsupported type: " + type);
     }

extensions/flac/src/androidTest/java/com/google/android/exoplayer/ext/flac/FlacPlaybackTest.java

@@ -19,6 +19,7 @@ import com.google.android.exoplayer.DefaultTrackSelector;
 import com.google.android.exoplayer.ExoPlaybackException;
 import com.google.android.exoplayer.ExoPlayer;
 import com.google.android.exoplayer.TrackRenderer;
+import com.google.android.exoplayer.extractor.Extractor;
 import com.google.android.exoplayer.extractor.ExtractorSampleSource;
 import com.google.android.exoplayer.extractor.mkv.MatroskaExtractor;
 import com.google.android.exoplayer.upstream.DefaultAllocator;
@@ -83,7 +84,7 @@ public class FlacPlaybackTest extends InstrumentationTestCase {
           new DefaultDataSource(context, null, Util.getUserAgent(context, "ExoPlayerExtFlacTest"),
               false),
           new DefaultAllocator(BUFFER_SEGMENT_SIZE), BUFFER_SEGMENT_SIZE * BUFFER_SEGMENT_COUNT,
-          new MatroskaExtractor());
+          new Extractor[] {new MatroskaExtractor()});
       player.setSource(sampleSource);
       player.setPlayWhenReady(true);
       Looper.loop();

extensions/opus/src/androidTest/java/com/google/android/exoplayer/ext/opus/OpusPlaybackTest.java

@@ -19,6 +19,7 @@ import com.google.android.exoplayer.DefaultTrackSelector;
 import com.google.android.exoplayer.ExoPlaybackException;
 import com.google.android.exoplayer.ExoPlayer;
 import com.google.android.exoplayer.TrackRenderer;
+import com.google.android.exoplayer.extractor.Extractor;
 import com.google.android.exoplayer.extractor.ExtractorSampleSource;
 import com.google.android.exoplayer.extractor.mkv.MatroskaExtractor;
 import com.google.android.exoplayer.upstream.DefaultAllocator;
@@ -83,7 +84,7 @@ public class OpusPlaybackTest extends InstrumentationTestCase {
           new DefaultDataSource(context, null, Util.getUserAgent(context, "ExoPlayerExtOpusTest"),
               false),
           new DefaultAllocator(BUFFER_SEGMENT_SIZE), BUFFER_SEGMENT_SIZE * BUFFER_SEGMENT_COUNT,
-          new MatroskaExtractor());
+          new Extractor[] {new MatroskaExtractor()});
       player.setSource(sampleSource);
       player.setPlayWhenReady(true);
       Looper.loop();

extensions/vp9/src/androidTest/java/com/google/android/exoplayer/ext/vp9/VpxPlaybackTest.java

@@ -19,6 +19,7 @@ import com.google.android.exoplayer.DefaultTrackSelector;
 import com.google.android.exoplayer.ExoPlaybackException;
 import com.google.android.exoplayer.ExoPlayer;
 import com.google.android.exoplayer.TrackRenderer;
+import com.google.android.exoplayer.extractor.Extractor;
 import com.google.android.exoplayer.extractor.ExtractorSampleSource;
 import com.google.android.exoplayer.extractor.mkv.MatroskaExtractor;
 import com.google.android.exoplayer.upstream.DefaultAllocator;
@@ -99,7 +100,7 @@ public class VpxPlaybackTest extends InstrumentationTestCase {
           new DefaultDataSource(context, null, Util.getUserAgent(context, "ExoPlayerExtVP9Test"),
               false),
           new DefaultAllocator(BUFFER_SEGMENT_SIZE), BUFFER_SEGMENT_SIZE * BUFFER_SEGMENT_COUNT,
-          new MatroskaExtractor());
+          new Extractor[] {new MatroskaExtractor()});
       player.sendMessage(videoRenderer, LibvpxVideoTrackRenderer.MSG_SET_OUTPUT_BUFFER_RENDERER,
           new VpxVideoSurfaceView(context));
       player.setSource(sampleSource);

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

@@ -108,94 +108,8 @@ public final class ExtractorSampleSource implements SampleSource, ExtractorOutpu
 
   private static final int MIN_RETRY_COUNT_DEFAULT_FOR_MEDIA = -1;
 
-  /**
+  // Lazily initialized default extractor classes in priority order.
-   * Default extractor classes in priority order. They are referred to indirectly so that it is
+  private static List<Class<? extends Extractor>> defaultExtractorClasses;
-   * possible to remove unused extractors.
-   */
-  private static final List<Class<? extends Extractor>> DEFAULT_EXTRACTOR_CLASSES;
-  static {
-    DEFAULT_EXTRACTOR_CLASSES = new ArrayList<>();
-    // Load extractors using reflection so that they can be deleted cleanly.
-    // Class.forName(<class name>) appears for each extractor so that automated tools like proguard
-    // can detect the use of reflection (see http://proguard.sourceforge.net/FAQ.html#forname).
-    try {
-      DEFAULT_EXTRACTOR_CLASSES.add(
-          Class.forName("com.google.android.exoplayer.extractor.mkv.MatroskaExtractor")
-              .asSubclass(Extractor.class));
-    } catch (ClassNotFoundException e) {
-      // Extractor not found.
-    }
-    try {
-      DEFAULT_EXTRACTOR_CLASSES.add(
-          Class.forName("com.google.android.exoplayer.extractor.mp4.FragmentedMp4Extractor")
-              .asSubclass(Extractor.class));
-    } catch (ClassNotFoundException e) {
-      // Extractor not found.
-    }
-    try {
-      DEFAULT_EXTRACTOR_CLASSES.add(
-          Class.forName("com.google.android.exoplayer.extractor.mp4.Mp4Extractor")
-              .asSubclass(Extractor.class));
-    } catch (ClassNotFoundException e) {
-      // Extractor not found.
-    }
-    try {
-      DEFAULT_EXTRACTOR_CLASSES.add(
-          Class.forName("com.google.android.exoplayer.extractor.mp3.Mp3Extractor")
-              .asSubclass(Extractor.class));
-    } catch (ClassNotFoundException e) {
-      // Extractor not found.
-    }
-    try {
-      DEFAULT_EXTRACTOR_CLASSES.add(
-          Class.forName("com.google.android.exoplayer.extractor.ts.AdtsExtractor")
-              .asSubclass(Extractor.class));
-    } catch (ClassNotFoundException e) {
-      // Extractor not found.
-    }
-    try {
-      DEFAULT_EXTRACTOR_CLASSES.add(
-          Class.forName("com.google.android.exoplayer.extractor.ts.TsExtractor")
-              .asSubclass(Extractor.class));
-    } catch (ClassNotFoundException e) {
-      // Extractor not found.
-    }
-    try {
-      DEFAULT_EXTRACTOR_CLASSES.add(
-          Class.forName("com.google.android.exoplayer.extractor.flv.FlvExtractor")
-              .asSubclass(Extractor.class));
-    } catch (ClassNotFoundException e) {
-      // Extractor not found.
-    }
-    try {
-      DEFAULT_EXTRACTOR_CLASSES.add(
-          Class.forName("com.google.android.exoplayer.extractor.ogg.OggExtractor")
-              .asSubclass(Extractor.class));
-    } catch (ClassNotFoundException e) {
-      // Extractor not found.
-    }
-    try {
-      DEFAULT_EXTRACTOR_CLASSES.add(
-          Class.forName("com.google.android.exoplayer.extractor.ts.PsExtractor")
-              .asSubclass(Extractor.class));
-    } catch (ClassNotFoundException e) {
-      // Extractor not found.
-    }
-    try {
-      DEFAULT_EXTRACTOR_CLASSES.add(
-          Class.forName("com.google.android.exoplayer.extractor.wav.WavExtractor")
-              .asSubclass(Extractor.class));
-    } catch (ClassNotFoundException e) {
-      // Extractor not found.
-    }
-    try {
-      DEFAULT_EXTRACTOR_CLASSES.add(
-          Class.forName("com.google.android.exoplayer.ext.flac.FlacExtractor")
-              .asSubclass(Extractor.class));
-    } catch (ClassNotFoundException e) {
-      // Extractor not found.
-    }
-  }
 
   private final Loader loader;
   private final ExtractorHolder extractorHolder;
@@ -235,11 +149,13 @@ public final class ExtractorSampleSource implements SampleSource, ExtractorOutpu
    * @param allocator An {@link Allocator} from which to obtain memory allocations.
    * @param requestedBufferSize The requested total buffer size for storing sample data, in bytes.
    *     The actual allocated size may exceed the value passed in if the implementation requires it.
-   * @param extractors {@link Extractor}s to extract the media stream, in order of decreasing
+   * @param extractors {@link Extractor}s to process the media stream. Where the possible formats
-   *     priority. If omitted, the default extractors will be used.
+   *     are known, instantiate and inject only instances of the corresponding {@link Extractor}s.
+   *     Where this is not possible, {@link #newDefaultExtractors()} can be used to construct an
+   *     array of default extractors.
    */
   public ExtractorSampleSource(Uri uri, DataSource dataSource, Allocator allocator,
-      int requestedBufferSize, Extractor... extractors) {
+      int requestedBufferSize, Extractor[] extractors) {
     this(uri, dataSource, allocator, requestedBufferSize, MIN_RETRY_COUNT_DEFAULT_FOR_MEDIA,
         extractors);
   }
@@ -254,12 +170,14 @@ public final class ExtractorSampleSource implements SampleSource, ExtractorOutpu
    *     null if delivery of events is not required.
    * @param eventListener A listener of events. May be null if delivery of events is not required.
    * @param eventSourceId An identifier that gets passed to {@code eventListener} methods.
-   * @param extractors {@link Extractor}s to extract the media stream, in order of decreasing
+   * @param extractors {@link Extractor}s to process the media stream. Where the possible formats
-   *     priority. If omitted, the default extractors will be used.
+   *     are known, instantiate and inject only instances of the corresponding {@link Extractor}s.
+   *     Where this is not possible, {@link #newDefaultExtractors()} can be used to construct an
+   *     array of default extractors.
    */
   public ExtractorSampleSource(Uri uri, DataSource dataSource, Allocator allocator,
       int requestedBufferSize, Handler eventHandler, EventListener eventListener,
-      int eventSourceId, Extractor... extractors) {
+      int eventSourceId, Extractor[] extractors) {
     this(uri, dataSource, allocator, requestedBufferSize, MIN_RETRY_COUNT_DEFAULT_FOR_MEDIA,
         eventHandler, eventListener, eventSourceId, extractors);
   }
@@ -272,11 +190,13 @@ public final class ExtractorSampleSource implements SampleSource, ExtractorOutpu
    *     The actual allocated size may exceed the value passed in if the implementation requires it.
    * @param minLoadableRetryCount The minimum number of times that the sample source will retry
    *     if a loading error occurs.
-   * @param extractors {@link Extractor}s to extract the media stream, in order of decreasing
+   * @param extractors {@link Extractor}s to process the media stream. Where the possible formats
-   *     priority. If omitted, the default extractors will be used.
+   *     are known, instantiate and inject only instances of the corresponding {@link Extractor}s.
+   *     Where this is not possible, {@link #newDefaultExtractors()} can be used to construct an
+   *     array of default extractors.
    */
   public ExtractorSampleSource(Uri uri, DataSource dataSource, Allocator allocator,
-      int requestedBufferSize, int minLoadableRetryCount, Extractor... extractors) {
+      int requestedBufferSize, int minLoadableRetryCount, Extractor[] extractors) {
     this(uri, dataSource, allocator, requestedBufferSize, minLoadableRetryCount, null, null, 0,
         extractors);
   }
@@ -293,12 +213,15 @@ public final class ExtractorSampleSource implements SampleSource, ExtractorOutpu
    *     null if delivery of events is not required.
    * @param eventListener A listener of events. May be null if delivery of events is not required.
    * @param eventSourceId An identifier that gets passed to {@code eventListener} methods.
-   * @param extractors {@link Extractor}s to extract the media stream, in order of decreasing
+   * @param extractors {@link Extractor}s to process the media stream. Where the possible formats
-   *     priority. If omitted, the default extractors will be used.
+   *     are known, instantiate and inject only instances of the corresponding {@link Extractor}s.
+   *     Where this is not possible {@link #newDefaultExtractors()} can be used to construct an
+   *     array of default extractors.
    */
   public ExtractorSampleSource(Uri uri, DataSource dataSource, Allocator allocator,
       int requestedBufferSize, int minLoadableRetryCount, Handler eventHandler,
-      EventListener eventListener, int eventSourceId, Extractor... extractors) {
+      EventListener eventListener, int eventSourceId, Extractor[] extractors) {
+    Assertions.checkState(extractors != null && extractors.length > 0);
     this.uri = uri;
     this.dataSource = dataSource;
     this.eventListener = eventListener;
@@ -311,21 +234,117 @@ public final class ExtractorSampleSource implements SampleSource, ExtractorOutpu
     int initialMinRetryCount = minLoadableRetryCount == MIN_RETRY_COUNT_DEFAULT_FOR_MEDIA
         ? DEFAULT_MIN_LOADABLE_RETRY_COUNT_ON_DEMAND : minLoadableRetryCount;
     loader = new Loader("Loader:ExtractorSampleSource", initialMinRetryCount);
-    if (extractors == null || extractors.length == 0) {
-      extractors = new Extractor[DEFAULT_EXTRACTOR_CLASSES.size()];
-      for (int i = 0; i < extractors.length; i++) {
-        try {
-          extractors[i] = DEFAULT_EXTRACTOR_CLASSES.get(i).newInstance();
-        } catch (Exception e) {
-          throw new IllegalStateException("Unexpected error creating default extractor", e);
-        }
-      }
-    }
     extractorHolder = new ExtractorHolder(extractors, this);
     pendingResetPositionUs = C.UNSET_TIME_US;
     sampleQueues = new DefaultTrackOutput[0];
   }
 
+  /**
+   * Builds default extractors that can be passed to an {@link ExtractorSampleSource} constructor.
+   *
+   * @return An array of default extractors.
+   */
+  public static Extractor[] newDefaultExtractors() {
+    synchronized (ExtractorSampleSource.class) {
+      if (defaultExtractorClasses == null) {
+        // Lazily initialize defaultExtractorClasses.
+        List<Class<? extends Extractor>> extractorClasses = new ArrayList<>();
+        // We reference extractors using reflection so that they can be deleted cleanly.
+        // Class.forName is used so that automated tools like proguard can detect the use of
+        // reflection (see http://proguard.sourceforge.net/FAQ.html#forname).
+        try {
+          extractorClasses.add(
+              Class.forName("com.google.android.exoplayer.extractor.mkv.MatroskaExtractor")
+              .asSubclass(Extractor.class));
+        } catch (ClassNotFoundException e) {
+          // Extractor not found.
+        }
+        try {
+          extractorClasses.add(
+              Class.forName("com.google.android.exoplayer.extractor.mp4.FragmentedMp4Extractor")
+              .asSubclass(Extractor.class));
+        } catch (ClassNotFoundException e) {
+          // Extractor not found.
+        }
+        try {
+          extractorClasses.add(
+              Class.forName("com.google.android.exoplayer.extractor.mp4.Mp4Extractor")
+              .asSubclass(Extractor.class));
+        } catch (ClassNotFoundException e) {
+          // Extractor not found.
+        }
+        try {
+          extractorClasses.add(
+              Class.forName("com.google.android.exoplayer.extractor.mp3.Mp3Extractor")
+              .asSubclass(Extractor.class));
+        } catch (ClassNotFoundException e) {
+          // Extractor not found.
+        }
+        try {
+          extractorClasses.add(
+              Class.forName("com.google.android.exoplayer.extractor.ts.AdtsExtractor")
+              .asSubclass(Extractor.class));
+        } catch (ClassNotFoundException e) {
+          // Extractor not found.
+        }
+        try {
+          extractorClasses.add(
+              Class.forName("com.google.android.exoplayer.extractor.ts.TsExtractor")
+              .asSubclass(Extractor.class));
+        } catch (ClassNotFoundException e) {
+          // Extractor not found.
+        }
+        try {
+          extractorClasses.add(
+              Class.forName("com.google.android.exoplayer.extractor.flv.FlvExtractor")
+              .asSubclass(Extractor.class));
+        } catch (ClassNotFoundException e) {
+          // Extractor not found.
+        }
+        try {
+          extractorClasses.add(
+              Class.forName("com.google.android.exoplayer.extractor.ogg.OggExtractor")
+              .asSubclass(Extractor.class));
+        } catch (ClassNotFoundException e) {
+          // Extractor not found.
+        }
+        try {
+          extractorClasses.add(
+              Class.forName("com.google.android.exoplayer.extractor.ts.PsExtractor")
+              .asSubclass(Extractor.class));
+        } catch (ClassNotFoundException e) {
+          // Extractor not found.
+        }
+        try {
+          extractorClasses.add(
+              Class.forName("com.google.android.exoplayer.extractor.wav.WavExtractor")
+              .asSubclass(Extractor.class));
+        } catch (ClassNotFoundException e) {
+          // Extractor not found.
+        }
+        try {
+          extractorClasses.add(
+              Class.forName("com.google.android.exoplayer.ext.flac.FlacExtractor")
+              .asSubclass(Extractor.class));
+        } catch (ClassNotFoundException e) {
+          // Extractor not found.
+        }
+        defaultExtractorClasses = extractorClasses;
+      }
+    }
+
+    Extractor[] extractors = new Extractor[defaultExtractorClasses.size()];
+    for (int i = 0; i < extractors.length; i++) {
+      try {
+        extractors[i] = defaultExtractorClasses.get(i).newInstance();
+      } catch (Exception e) {
+        // Should never happen.
+        throw new IllegalStateException("Unexpected error creating default extractor", e);
+      }
+    }
+    return extractors;
+  }
+
   // SampleSource implementation.
 
   @Override