Add enumerations for compressed (E)AC3 sample format

media/base/audio_parameters.h

Index: media/base/audio_parameters.h
diff --git a/media/base/audio_parameters.h b/media/base/audio_parameters.h
index 2cb28c64bdfd5688f244324d1d80df0ba8fb9005..d2628538e14b16881ba251f40164811981a1172a 100644
--- a/media/base/audio_parameters.h
+++ b/media/base/audio_parameters.h
@@ -72,6 +72,8 @@ class MEDIA_EXPORT AudioParameters {
   enum Format {
     AUDIO_PCM_LINEAR = 0,            // PCM is 'raw' amplitude samples.
     AUDIO_PCM_LOW_LATENCY,           // Linear PCM, low latency requested.
+    AUDIO_BITSTREAM_AC3,             // Compressed AC3 bitstream.
+    AUDIO_BITSTREAM_EAC3,            // Compressed E-AC3 bitstream.
     AUDIO_FAKE,                      // Creates a fake AudioOutputStream object.
     AUDIO_FORMAT_LAST = AUDIO_FAKE,  // Only used for validation of format.
   };
@@ -139,6 +141,9 @@ class MEDIA_EXPORT AudioParameters {
   // Comparison with other AudioParams.
   bool Equals(const AudioParameters& other) const;
 
+  // Return true if |format_| is compressed audio.
+  bool IsCompressedFormat() const;
+
   void set_format(Format format) { format_ = format; }
   Format format() const { return format_; }