FMP4 EMSG/CEA608 output bug fix + tweaks

- Fix to use different track ids for EMSG + CEA608, so they can
  both be enabled at once.
- Tweaked extractor to output formats prior to endTracks() when
  parsing the initial moov box. This makes it easier to handle
  multiple tracks through the chunk package. It may or may not
  be made a requirement (it's already true for the MKV extractor).

Issue: #2362
Issue: #2176

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=145538757

library/src/main/java/com/google/android/exoplayer2/extractor/mp4/FragmentedMp4Extractor.java

@@ -420,19 +420,19 @@ private void onMoovContainerAtomRead(ContainerAtom moov) throws ParserException
       // We need to create the track bundles.
       for (int i = 0; i < trackCount; i++) {
         Track track = tracks.valueAt(i);
-        trackBundles.put(track.id, new TrackBundle(extractorOutput.track(i)));
+        TrackBundle trackBundle = new TrackBundle(extractorOutput.track(i));
+        trackBundle.init(track, defaultSampleValuesArray.get(track.id));
+        trackBundles.put(track.id, trackBundle);
         durationUs = Math.max(durationUs, track.durationUs);
       }
       maybeInitExtraTracks();
       extractorOutput.endTracks();
     } else {
       Assertions.checkState(trackBundles.size() == trackCount);
-    }
-
-    // Initialization of tracks and default sample values.
-    for (int i = 0; i < trackCount; i++) {
-      Track track = tracks.valueAt(i);
-      trackBundles.get(track.id).init(track, defaultSampleValuesArray.get(track.id));
+      for (int i = 0; i < trackCount; i++) {
+        Track track = tracks.valueAt(i);
+        trackBundles.get(track.id).init(track, defaultSampleValuesArray.get(track.id));
+      }
     }
   }
 
@@ -454,7 +454,7 @@ private void maybeInitExtraTracks() {
           Format.OFFSET_SAMPLE_RELATIVE));
     }
     if ((flags & FLAG_ENABLE_CEA608_TRACK) != 0 && cea608TrackOutput == null) {
-      cea608TrackOutput = extractorOutput.track(trackBundles.size());
+      cea608TrackOutput = extractorOutput.track(trackBundles.size() + 1);
       cea608TrackOutput.format(Format.createTextSampleFormat(null, MimeTypes.APPLICATION_CEA608,
           null, Format.NO_VALUE, 0, null, null));
     }