message: Delete unused enum ProtectionType
  Unused since cl
  Cr-Commit-Position: refs/heads/master@{#28161}
diff: @@ -43,8 +43,6 @@ const int kBogusRtpRateForAudioRtcp = 8000;
  // Minimum RTP header size in bytes.
  const uint8_t kRtpHeaderSize = 12;
  -enum ProtectionType { kUnprotectedPacket, kProtectedPacket };
  -
  enum StorageType { kDontRetransmit, kAllowRetransmission };
  bool IsLegalMidName(absl::string_view name);
  