Enable setting the maximum bitrate limit in RtpSender.

webrtc/media/base/mediaengine.h

Index: webrtc/media/base/mediaengine.h
diff --git a/webrtc/media/base/mediaengine.h b/webrtc/media/base/mediaengine.h
index 479d1acf4e820af67f8bbf925eac50700c9dfb2a..883c34c834fb3d9181b21637c4d92c07948d7c91 100644
--- a/webrtc/media/base/mediaengine.h
+++ b/webrtc/media/base/mediaengine.h
@@ -19,6 +19,7 @@
 #include <vector>
 
 #include "webrtc/audio_state.h"
+#include "webrtc/api/rtpparameters.h"
 #include "webrtc/base/fileutils.h"
 #include "webrtc/base/sigslotrepeater.h"
 #include "webrtc/media/base/codec.h"
@@ -205,6 +206,8 @@ class DataEngineInterface {
   virtual const std::vector<DataCodec>& data_codecs() = 0;
 };
 
+webrtc::RtpParameters CreateRtpParametersWithOneEncoding();
+
 }  // namespace cricket
 
 #endif  // WEBRTC_MEDIA_BASE_MEDIAENGINE_H_