Add support for GCM cipher suites from RFC 7714.

webrtc/base/opensslstreamadapter.cc

Index: webrtc/base/opensslstreamadapter.cc
diff --git a/webrtc/base/opensslstreamadapter.cc b/webrtc/base/opensslstreamadapter.cc
index abdf5e4834cdecaa6319766e4147d4ea713e525e..ed7371a7c2bf7b4ecf23f6cb2c3bdc2492c14530 100644
--- a/webrtc/base/opensslstreamadapter.cc
+++ b/webrtc/base/opensslstreamadapter.cc
@@ -55,6 +55,8 @@ struct SrtpCipherMapEntry {
 static SrtpCipherMapEntry SrtpCipherMap[] = {
     {"SRTP_AES128_CM_SHA1_80", SRTP_AES128_CM_SHA1_80},
     {"SRTP_AES128_CM_SHA1_32", SRTP_AES128_CM_SHA1_32},
+    {"SRTP_AEAD_AES_128_GCM", SRTP_AEAD_AES_128_GCM},
+    {"SRTP_AEAD_AES_256_GCM", SRTP_AEAD_AES_256_GCM},
     {nullptr, 0}};
 #endif