Let the mp4 extractor support "camm" metadata tracks.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=139626848

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

@@ -133,6 +133,7 @@ import java.util.List;
   public static final int TYPE_vp08 = Util.getIntegerCodeForString("vp08");
   public static final int TYPE_vp09 = Util.getIntegerCodeForString("vp09");
   public static final int TYPE_vpcC = Util.getIntegerCodeForString("vpcC");
+  public static final int TYPE_camm = Util.getIntegerCodeForString("camm");
 
   public final int type;
 

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

@@ -50,6 +50,7 @@ import java.util.List;
   private static final int TYPE_subt = Util.getIntegerCodeForString("subt");
   private static final int TYPE_clcp = Util.getIntegerCodeForString("clcp");
   private static final int TYPE_cenc = Util.getIntegerCodeForString("cenc");
+  private static final int TYPE_meta = Util.getIntegerCodeForString("meta");
 
   /**
    * Parses a trak atom (defined in 14496-12).
@@ -541,6 +542,8 @@ import java.util.List;
     } else if (trackType == TYPE_text || trackType == TYPE_sbtl || trackType == TYPE_subt
         || trackType == TYPE_clcp) {
       return C.TRACK_TYPE_TEXT;
+    } else if (trackType == TYPE_meta) {
+      return C.TRACK_TYPE_METADATA;
     } else {
       return C.TRACK_TYPE_UNKNOWN;
     }
@@ -621,6 +624,9 @@ import java.util.List;
         out.format = Format.createTextSampleFormat(Integer.toString(trackId),
             MimeTypes.APPLICATION_CEA608, null, Format.NO_VALUE, 0, language, drmInitData);
         out.requiredSampleTransformation = Track.TRANSFORMATION_CEA608_CDAT;
+      } else if (childAtomType == Atom.TYPE_camm) {
+        out.format = Format.createSampleFormat(Integer.toString(trackId),
+            MimeTypes.APPLICATION_CAMERA_MOTION, null, Format.NO_VALUE, drmInitData);
       }
       stsd.setPosition(childStartPosition + childAtomSize);
     }

library/src/main/java/com/google/android/exoplayer2/util/MimeTypes.java

@@ -75,6 +75,7 @@ public final class MimeTypes {
   public static final String APPLICATION_VOBSUB = BASE_TYPE_APPLICATION + "/vobsub";
   public static final String APPLICATION_PGS = BASE_TYPE_APPLICATION + "/pgs";
   public static final String APPLICATION_SCTE35 = BASE_TYPE_APPLICATION + "/x-scte35";
+  public static final String APPLICATION_CAMERA_MOTION = BASE_TYPE_APPLICATION + "/x-camera-motion";
 
   private MimeTypes() {}