Refactoring: Use enum for RtpPayloadType.

media/cast/net/cast_transport_config.h

Index: media/cast/net/cast_transport_config.h
diff --git a/media/cast/net/cast_transport_config.h b/media/cast/net/cast_transport_config.h
index dddc94696eecaf85a324fa9cb10baf305155d945..1ff840cbf60f2bb6e2c4b686f9f795bd2e7f1ec2 100644
--- a/media/cast/net/cast_transport_config.h
+++ b/media/cast/net/cast_transport_config.h
@@ -30,6 +30,34 @@ enum Codec {
   CODEC_LAST = CODEC_VIDEO_H264
 };
 
+// Describes the content being transported over RTP streams.
+enum RtpPayloadType {

[miu, 2016/06/20 21:00:27]

nit style suggestion: Use an enum class:

  enum class RtpPayloadType : int {
    UNKNOWN,
    AUDIO_OPUS = 96,
    AUDIO_AAC,
    ...
  };

[xjz, 2016/06/21 17:24:31]

Done.

+  RTP_PAYLOAD_UNKNOWN,
+
+  // Cast Streaming will encode raw audio frames using one of its available
+  // codec implementations, and transport encoded data in the RTP stream.
+  RTP_PAYLOAD_AUDIO_OPUS = 96,

[miu, 2016/06/20 21:00:27]

If we add new ones in the future, the numbering might become messed up (if any
code depends on it). You might just assign an explicit value to each of these
(97 for AAC, 98 for PCM16, and so on).

[xjz, 2016/06/21 17:24:31]

Done.

+  RTP_PAYLOAD_AUDIO_AAC,
+  RTP_PAYLOAD_AUDIO_PCM16,
+
+  // Audio frame data is not modified, and should be transported reliably and
+  // in-sequence. No assumptions about the data can be made.
+  RTP_PAYLOAD_REMOTE_AUDIO,
+
+  RTP_PAYLOAD_AUDIO_LAST = RTP_PAYLOAD_REMOTE_AUDIO,
+
+  // Cast Streaming will encode raw video frames using one of its available
+  // codec implementations, and transport encoded data in the RTP stream.
+  RTP_PAYLOAD_VIDEO_VP8,
+  RTP_PAYLOAD_VIDEO_H264,
+
+  // Video frame data is not modified, and should be transported reliably and
+  // in-sequence. No assumptions about the data can be made.
+  RTP_PAYLOAD_REMOTE_VIDEO,
+
+  RTP_PAYLOAD_VIDEO_LAST = RTP_PAYLOAD_REMOTE_VIDEO
+};
+
 struct CastTransportRtpConfig {
   CastTransportRtpConfig();
   ~CastTransportRtpConfig();
@@ -41,7 +69,7 @@ struct CastTransportRtpConfig {
   uint32_t feedback_ssrc;
 
   // RTP payload type enum: Specifies the type/encoding of frame data.
-  int rtp_payload_type;
+  RtpPayloadType rtp_payload_type;
 
   // The AES crypto key and initialization vector.  Each of these strings
   // contains the data in binary form, of size kAesKeySize.  If they are empty