Support Ogg containers without a properly flagged last page.

Such files are slightly off spec but easy to support.(https://github.com/google/ExoPlayer/issues/1506)
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=121927762

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

@@ -112,12 +112,9 @@ import java.io.IOException;
     Assertions.checkArgument(input.getLength() != C.LENGTH_UNBOUNDED); // never read forever!
     Assertions.checkArgument(input.getLength() != C.LENGTH_UNBOUNDED); // never read forever!
     OggUtil.skipToNextPage(input);
     OggUtil.skipToNextPage(input);
     pageHeader.reset();
     pageHeader.reset();
-    while ((pageHeader.type & 0x04) != 0x04) {
-      if (pageHeader.bodySize > 0) {
-        input.skipFully(pageHeader.bodySize);
-      }
+    while ((pageHeader.type & 0x04) != 0x04 && input.getPosition() < input.getLength()) {
       OggUtil.populatePageHeader(input, pageHeader, headerArray, false);
       OggUtil.populatePageHeader(input, pageHeader, headerArray, false);
-      input.skipFully(pageHeader.headerSize);
+      input.skipFully(pageHeader.headerSize + pageHeader.bodySize);
     }
     }
     return pageHeader.granulePosition;
     return pageHeader.granulePosition;
   }
   }

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

@@ -34,6 +34,8 @@ import java.util.ArrayList;
  */
  */
 /* package */ final class VorbisReader extends StreamReader implements SeekMap {
 /* package */ final class VorbisReader extends StreamReader implements SeekMap {
 
 
+  private static final long LARGEST_EXPECTED_PAGE_SIZE = 8000;
+
   private VorbisSetup vorbisSetup;
   private VorbisSetup vorbisSetup;
   private int previousPacketBlockSize;
   private int previousPacketBlockSize;
   private long elapsedSamples;
   private long elapsedSamples;
@@ -78,7 +80,7 @@ import java.util.ArrayList;
         extractorOutput.seekMap(this);
         extractorOutput.seekMap(this);
         if (inputLength != C.LENGTH_UNBOUNDED) {
         if (inputLength != C.LENGTH_UNBOUNDED) {
           // seek to the end just before the last page of stream to get the duration
           // seek to the end just before the last page of stream to get the duration
-          seekPosition.position = input.getLength() - 8000;
+          seekPosition.position = Math.max(0, input.getLength() - LARGEST_EXPECTED_PAGE_SIZE);
           return Extractor.RESULT_SEEK;
           return Extractor.RESULT_SEEK;
         }
         }
       }
       }