Add support for GCM cipher suites from RFC 7714.

talk/app/webrtc/peerconnectioninterface.h

Index: talk/app/webrtc/peerconnectioninterface.h
diff --git a/talk/app/webrtc/peerconnectioninterface.h b/talk/app/webrtc/peerconnectioninterface.h
index 100d8cea07b1397f115dae47f0944b1f23ba8377..2ef26f00dcfb08123e2d4358ecf991d233cb8c46 100644
--- a/talk/app/webrtc/peerconnectioninterface.h
+++ b/talk/app/webrtc/peerconnectioninterface.h
@@ -548,7 +548,8 @@ class PeerConnectionFactoryInterface : public rtc::RefCountInterface {
       disable_sctp_data_channels(false),
       disable_network_monitor(false),
       network_ignore_mask(rtc::kDefaultNetworkIgnoreMask),
-      ssl_max_version(rtc::SSL_PROTOCOL_DTLS_10) {
+      ssl_max_version(rtc::SSL_PROTOCOL_DTLS_10),
+      enable_gcm_crypto_suites(false) {
     }
     bool disable_encryption;
     bool disable_sctp_data_channels;
@@ -563,6 +564,10 @@ class PeerConnectionFactoryInterface : public rtc::RefCountInterface {
     // supported by both ends will be used for the connection, i.e. if one
     // party supports DTLS 1.0 and the other DTLS 1.2, DTLS 1.0 will be used.
     rtc::SSLProtocolVersion ssl_max_version;
+
+    // Enable GCM crypto suites from RFC 7714 for SRTP. GCM will only be used
+    // if both sides enable it.
+    bool enable_gcm_crypto_suites;
   };
 
   virtual void SetOptions(const Options& options) = 0;