Add CreateSessionDescription overload which takes a cricket::SessionDescription

This gives clients a way to create a SessionDescriptionInterface
from a parsed cricket::SessionDescription other than depending on
JsepSessionDescription.

Bug: webrtc:9544
Change-Id: I3eec87b24aa005e6cbc4a018ad452c0d6823435d
Reviewed-on: https://webrtc-review.googlesource.com/90382
Reviewed-by: Seth Hampson <shampson@webrtc.org>
Commit-Queue: Steve Anton <steveanton@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24105}
diff --git a/api/jsep.h b/api/jsep.h
index cbc0a6c..4d4bcc0 100644
--- a/api/jsep.h
+++ b/api/jsep.h
@@ -197,6 +197,14 @@
     const std::string& sdp,
     SdpParseError* error_out);
 
+// Creates a SessionDescriptionInterface based on a parsed SDP structure and the
+// given type, ID and version.
+std::unique_ptr<SessionDescriptionInterface> CreateSessionDescription(
+    SdpType type,
+    const std::string& session_id,
+    const std::string& session_version,
+    std::unique_ptr<cricket::SessionDescription> description);
+
 // CreateOffer and CreateAnswer callback interface.
 class CreateSessionDescriptionObserver : public rtc::RefCountInterface {
  public: