Only use BoringSSL time callback in unit tests.

webrtc/base/sslstreamadapter.h

Index: webrtc/base/sslstreamadapter.h
diff --git a/webrtc/base/sslstreamadapter.h b/webrtc/base/sslstreamadapter.h
index 2b99f00cb307eed1aaa3aa210eae8aebe299fd8d..391019165ff9558efaf8e41ff85f4dc877f73d92 100644
--- a/webrtc/base/sslstreamadapter.h
+++ b/webrtc/base/sslstreamadapter.h
@@ -244,6 +244,10 @@ class SSLStreamAdapter : public StreamAdapterInterface {
   // depending on specific SSL implementation.
   static std::string SslCipherSuiteToName(int cipher_suite);
 
+  // Use our timeutils.h source of timing in BoringSSL, allowing us to test
+  // using a fake clock.
+  static void enable_time_callback_for_testing();
+
   sigslot::signal1<SSLHandshakeError> SignalSSLHandshakeError;
 
  private: