Add PeerConnection GetRtpSender/ReceiverCapabilities

Those are static functions in the spec, so implemented as member functions
of the PeerConnectionFactory instead.

Bug: webrtc:7577, webrtc:9441
Change-Id: Iccb24180e096e713d24e7e25ecfd5d7bbd7638f9
Reviewed-on: https://webrtc-review.googlesource.com/85341
Commit-Queue: Florent Castelli <orphis@webrtc.org>
Reviewed-by: Taylor Brandstetter <deadbeef@webrtc.org>
Reviewed-by: Steve Anton <steveanton@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23768}
diff --git a/api/peerconnectionfactoryproxy.h b/api/peerconnectionfactoryproxy.h
index eea5b55..db52083 100644
--- a/api/peerconnectionfactoryproxy.h
+++ b/api/peerconnectionfactoryproxy.h
@@ -48,6 +48,12 @@
               CreatePeerConnection,
               const PeerConnectionInterface::RTCConfiguration&,
               PeerConnectionDependencies);
+PROXY_CONSTMETHOD1(webrtc::RtpCapabilities,
+                   GetRtpSenderCapabilities,
+                   cricket::MediaType);
+PROXY_CONSTMETHOD1(webrtc::RtpCapabilities,
+                   GetRtpReceiverCapabilities,
+                   cricket::MediaType);
 PROXY_METHOD1(rtc::scoped_refptr<MediaStreamInterface>,
               CreateLocalMediaStream,
               const std::string&)