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

webrtc/p2p/base/dtlstransportinternal.h

Index: webrtc/p2p/base/dtlstransportinternal.h
diff --git a/webrtc/p2p/base/dtlstransportinternal.h b/webrtc/p2p/base/dtlstransportinternal.h
index 7a1e8ad3e985a7f05680d5cd0f7890fe981968c8..9ec46639d4549405f482320f9cc101afdb2b72df 100644
--- a/webrtc/p2p/base/dtlstransportinternal.h
+++ b/webrtc/p2p/base/dtlstransportinternal.h
@@ -29,7 +29,9 @@ enum PacketFlags {
                           // crypto provided by the transport (e.g. DTLS)
 };
 
-// DtlsTransportInternal is an internal interface that does DTLS.
+// DtlsTransportInternal is an internal interface that does DTLS, also
+// negotiating SRTP crypto suites so that it may be used for DTLS-SRTP.
+//
 // Once the public interface is supported,
 // (https://www.w3.org/TR/webrtc/#rtcdtlstransport-interface)
 // the DtlsTransportInterface will be split from this class.
@@ -49,13 +51,6 @@ class DtlsTransportInternal : public rtc::PacketTransportInternal {
 
   virtual bool SetSslRole(rtc::SSLRole role) = 0;
 
-  // Sets up the ciphers to use for DTLS-SRTP.
-  virtual bool SetSrtpCryptoSuites(const std::vector<int>& ciphers) = 0;
-
-  // Keep the original one for backward compatibility until all dependencies
-  // move away. TODO(zhihuang): Remove this function.
-  virtual bool SetSrtpCiphers(const std::vector<std::string>& ciphers) = 0;
-
   // Finds out which DTLS-SRTP cipher was negotiated.
   // TODO(zhihuang): Remove this once all dependencies implement this.
   virtual bool GetSrtpCryptoSuite(int* cipher) = 0;