Negotiate the same SRTP crypto suites for every DTLS association formed.

webrtc/api/peerconnectioninterface.h

Index: webrtc/api/peerconnectioninterface.h
diff --git a/webrtc/api/peerconnectioninterface.h b/webrtc/api/peerconnectioninterface.h
index e384fba3dbc2adbe4dabdc324e5d4624cdc9a424..401ef0480b07d22e1658b932bec8a3a2eec60d59 100644
--- a/webrtc/api/peerconnectioninterface.h
+++ b/webrtc/api/peerconnectioninterface.h
@@ -882,6 +882,7 @@ class PeerConnectionFactoryInterface : public rtc::RefCountInterface {
     rtc::CryptoOptions crypto_options;
   };
 
+  // Set the options to be used for subsequently created PeerConnections.
   virtual void SetOptions(const Options& options) = 0;
 
   // |allocator| and |cert_generator| may be null, in which case default