Add FlexfecReceiveStream.

webrtc/config.h

Index: webrtc/config.h
diff --git a/webrtc/config.h b/webrtc/config.h
index a6778715d87f634692a63b59aac64d3010ec73c6..4ec895b0dd8265b34043a75cb082575ffb29dc7f 100644
--- a/webrtc/config.h
+++ b/webrtc/config.h
@@ -16,6 +16,7 @@
 #include <string>
 #include <vector>
 
+#include "webrtc/base/basictypes.h"
 #include "webrtc/base/optional.h"
 #include "webrtc/base/refcount.h"
 #include "webrtc/base/scoped_ref_ptr.h"
@@ -53,6 +54,26 @@ struct UlpfecConfig {
   int red_rtx_payload_type;
 };
 
+// Settings for FlexFEC forward error correction.
+// Set the payload type to '-1' to disable.
+struct FlexfecConfig {
+  FlexfecConfig()
+      : flexfec_payload_type(-1), flexfec_ssrc(0), protected_media_ssrcs() {}
+  std::string ToString() const;
+
+  // Payload type of FlexFEC.
+  int flexfec_payload_type;
+
+  // SSRC of FlexFEC stream.
+  uint32_t flexfec_ssrc;
+
+  // Vector containing a single element, corresponding to the SSRC of the media
+  // stream being protected by this FlexFEC stream. The vector MUST have size 1.
+  //
+  // TODO(brandtr): Update comment above when we support multistream protection.
+  std::vector<uint32_t> protected_media_ssrcs;
+};
+
 // RTP header extension, see RFC 5285.
 struct RtpExtension {
   RtpExtension() : id(0) {}