Revert of Removing #defines previously used for building without BoringSSL/OpenSSL.

webrtc/base/sslstreamadapter.h

Index: webrtc/base/sslstreamadapter.h
diff --git a/webrtc/base/sslstreamadapter.h b/webrtc/base/sslstreamadapter.h
index 4f5ee02fe44343fb7028e5f9ca354a371ff50d9d..391019165ff9558efaf8e41ff85f4dc877f73d92 100644
--- a/webrtc/base/sslstreamadapter.h
+++ b/webrtc/base/sslstreamadapter.h
@@ -228,9 +228,10 @@
   // SS_OPENING but IsTlsConnected should return true.
   virtual bool IsTlsConnected() = 0;
 
-  // Capabilities testing.
-  // Used to have "DTLS supported", "DTLS-SRTP supported" etc. methods, but now
-  // that's assumed.
+  // Capabilities testing
+  static bool HaveDtls();
+  static bool HaveDtlsSrtp();
+  static bool HaveExporter();
   static bool IsBoringSsl();
 
   // Returns true iff the supplied cipher is deemed to be strong.