Fix Ogg/Flac sync exception.

Restores input position after flac block size read.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=122978325

library/src/androidTest/java/com/google/android/exoplayer/extractor/ogg/OggExtractorFileTests.java

@@ -43,10 +43,20 @@ public final class OggExtractorFileTests extends InstrumentationTestCase {
   }
 
   public void testFlac() throws Exception {
-    parseFile(FLAC_TEST_FILE, false, false, false, MimeTypes.AUDIO_FLAC, 2741000, 33);
-    parseFile(FLAC_TEST_FILE, false, true, false, MimeTypes.AUDIO_FLAC, 2741000, 33);
-    parseFile(FLAC_TEST_FILE, true, false, true, MimeTypes.AUDIO_FLAC, 2741000, 33);
-    parseFile(FLAC_TEST_FILE, true, true, true, MimeTypes.AUDIO_FLAC, 2741000, 33);
+    testFlac(false, false, false);
+    testFlac(false, true, false);
+    testFlac(true, false, true);
+    testFlac(true, true, true);
+  }
+
+  private void testFlac(boolean simulateIOErrors, boolean simulateUnknownLength,
+      boolean simulatePartialReads) throws Exception {
+    FakeTrackOutput trackOutput = parseFile(FLAC_TEST_FILE, simulateIOErrors, simulateUnknownLength,
+        simulatePartialReads, MimeTypes.AUDIO_FLAC, 2741000, 33);
+    for (int i = 0; i < 33; i++) {
+      byte[] sampleData = trackOutput.getSampleData(i);
+      assertTrue(FlacReader.isAudioPacket(sampleData));
+    }
   }
 
   public void testFlacNoSeektable() throws Exception {
@@ -56,10 +66,9 @@ public final class OggExtractorFileTests extends InstrumentationTestCase {
     parseFile(FLAC_NS_TEST_FILE, true, true, true, MimeTypes.AUDIO_FLAC, C.UNSET_TIME_US, 33);
   }
 
-  private void parseFile(String testFile, boolean simulateIOErrors, boolean simulateUnknownLength,
-      boolean simulatePartialReads, String expectedMimeType, long expectedDuration,
-      int expectedSampleCount)
-      throws Exception {
+  private FakeTrackOutput parseFile(String testFile, boolean simulateIOErrors,
+      boolean simulateUnknownLength, boolean simulatePartialReads, String expectedMimeType,
+      long expectedDuration, int expectedSampleCount) throws Exception {
     byte[] fileData = TestUtil.getByteArray(getInstrumentation(), testFile);
     FakeExtractorInput input = new FakeExtractorInput.Builder().setData(fileData)
         .setSimulateIOErrors(simulateIOErrors)
@@ -89,6 +98,7 @@ public final class OggExtractorFileTests extends InstrumentationTestCase {
     assertEquals(expectedDuration != C.UNSET_TIME_US, seekMap.isSeekable());
 
     trackOutput.assertSampleCount(expectedSampleCount);
+    return trackOutput;
   }
 
 }

library/src/androidTest/java/com/google/android/exoplayer/testutil/FakeTrackOutput.java

@@ -21,7 +21,6 @@ import com.google.android.exoplayer.extractor.TrackOutput;
 import com.google.android.exoplayer.util.ParsableByteArray;
 
 import android.test.MoreAsserts;
-
 import junit.framework.Assert;
 
 import java.io.IOException;
@@ -86,8 +85,7 @@ public final class FakeTrackOutput implements TrackOutput {
   }
 
   public void assertSample(int index, byte[] data, long timeUs, int flags, byte[] encryptionKey) {
-    byte[] actualData = Arrays.copyOfRange(sampleData, sampleStartOffsets.get(index),
-        sampleEndOffsets.get(index));
+    byte[] actualData = getSampleData(index);
     MoreAsserts.assertEquals(data, actualData);
     Assert.assertEquals(timeUs, (long) sampleTimesUs.get(index));
     Assert.assertEquals(flags, (int) sampleFlags.get(index));
@@ -99,6 +97,11 @@ public final class FakeTrackOutput implements TrackOutput {
     }
   }
 
+  public byte[] getSampleData(int index) {
+    return Arrays.copyOfRange(sampleData, sampleStartOffsets.get(index),
+        sampleEndOffsets.get(index));
+  }
+
   public void assertEquals(FakeTrackOutput expected) {
     Assert.assertEquals(expected.format, format);
     Assert.assertEquals(expected.sampleTimesUs.size(), sampleTimesUs.size());

library/src/main/java/com/google/android/exoplayer/extractor/ogg/FlacReader.java

@@ -47,9 +47,14 @@ import java.util.List;
         data.readUnsignedInt() == 0x464C4143; // ASCII signature "FLAC"
   }
 
+  //@VisibleForTesting
+  public static boolean isAudioPacket(byte[] data) {
+    return data[0] == AUDIO_PACKET_TYPE;
+  }
+
   @Override
   protected long preparePayload(ParsableByteArray packet) {
-    if (packet.data[0] != AUDIO_PACKET_TYPE) {
+    if (!isAudioPacket(packet.data)) {
       return -1;
     }
     return getFlacFrameBlockSize(packet);
@@ -71,7 +76,7 @@ import java.util.List;
       Assertions.checkArgument(flacOggSeeker == null);
       flacOggSeeker = new FlacOggSeeker();
       flacOggSeeker.parseSeekTable(packet);
-    } else if (data[0] == AUDIO_PACKET_TYPE) {
+    } else if (isAudioPacket(data)) {
       if (flacOggSeeker != null) {
         flacOggSeeker.setFirstFrameOffset(position);
         setupData.oggSeeker = flacOggSeeker;
@@ -96,11 +101,9 @@ import java.util.List;
         // skip the sample number
         packet.skipBytes(FRAME_HEADER_SAMPLE_NUMBER_OFFSET);
         packet.readUtf8EncodedLong();
-        if (blockSizeCode == 6) {
-          return packet.readUnsignedByte() + 1;
-        } else {
-          return packet.readUnsignedShort() + 1;
-        }
+        int value = blockSizeCode == 6 ? packet.readUnsignedByte() : packet.readUnsignedShort();
+        packet.setPosition(0);
+        return value + 1;
       case 8:
       case 9:
       case 10: