Reland of Moving MediaStreamSignaling logic into PeerConnection.

talk/app/webrtc/sctputils.h

Index: talk/app/webrtc/sctputils.h
diff --git a/talk/app/webrtc/sctputils.h b/talk/app/webrtc/sctputils.h
index ab1818bcf8ddf6d39263deed07d69b0cc4b4906a..f16873c4c3d66d59a56b65f60890e125b64d690c 100644
--- a/talk/app/webrtc/sctputils.h
+++ b/talk/app/webrtc/sctputils.h
@@ -39,6 +39,9 @@ class Buffer;
 namespace webrtc {
 struct DataChannelInit;
 
+// Read the message type and return true if it's an OPEN message.
+bool IsOpenMessage(const rtc::Buffer& payload);
+
 bool ParseDataChannelOpenMessage(const rtc::Buffer& payload,
                                  std::string* label,
                                  DataChannelInit* config);