Add enumerations for compressed (E)AC3 sample format

media/base/sample_format.h

Index: media/base/sample_format.h
diff --git a/media/base/sample_format.h b/media/base/sample_format.h
index 24bbe4f59ed7cc41643021e6e7547ef0fd6cf9f2..121b98310f319aedf6846917479a99089e0f7799 100644
--- a/media/base/sample_format.h
+++ b/media/base/sample_format.h
@@ -23,9 +23,11 @@ enum SampleFormat {
   kSampleFormatPlanarF32,  // Float 32-bit planar.
   kSampleFormatPlanarS32,  // Signed 32-bit planar.
   kSampleFormatS24,        // Signed 24-bit.
+  kSampleFormatAc3,        // Compressed AC3 bitstream.
+  kSampleFormatEac3,       // Compressed E-AC3 bitstream.
 
   // Must always be equal to largest value ever logged.
-  kSampleFormatMax = kSampleFormatS24,
+  kSampleFormatMax = kSampleFormatEac3,
 };
 
 // Returns the number of bytes used per channel for the specified
@@ -41,6 +43,9 @@ MEDIA_EXPORT bool IsPlanar(SampleFormat sample_format);
 // Returns true if |sample_format| is interleaved, false otherwise.
 MEDIA_EXPORT bool IsInterleaved(SampleFormat sample_format);
 
+// Returns true if |sample_format| is compressed bitstream, false otherwise.
+MEDIA_EXPORT bool IsBitstream(SampleFormat sample_format);
+
 }  // namespace media
 
 #endif  // MEDIA_BASE_SAMPLE_FORMAT_H_