Support EAC3 (Dolby Digital Plus) codec

media/mp4/es_descriptor.h

Index: media/mp4/es_descriptor.h
diff --git a/media/mp4/es_descriptor.h b/media/mp4/es_descriptor.h
index 65b9cd27121a8ef9cd8a7fbe557a214aebacb07f..36e1bf2a3b14ffae1a99f083dce394766f768b95 100644
--- a/media/mp4/es_descriptor.h
+++ b/media/mp4/es_descriptor.h
@@ -21,7 +21,8 @@ namespace mp4 {
 enum ObjectType {
   kForbidden = 0,
   kISO_14496_3 = 0x40,  // MPEG4 AAC
-  kISO_13818_7_AAC_LC = 0x67  // MPEG2 AAC-LC
+  kISO_13818_7_AAC_LC = 0x67,  // MPEG2 AAC-LC
+  kEAC3 = 0xa6  // Dolby Digital Plus
 };
 
 // This class parse object type and decoder specific information from an
@@ -29,6 +30,9 @@ enum ObjectType {
 // Please refer to ISO 14496 Part 1 7.2.6.5 for more details.
 class MEDIA_EXPORT ESDescriptor {
  public:
+  // Utility function to check if the given object type is AAC.
+  static bool IsAAC(uint8 object_type);
+
   ESDescriptor();
   ~ESDescriptor();