Make CertVerifier a pure virtual interface.

remoting/protocol/ssl_hmac_channel_authenticator.cc

Index: remoting/protocol/ssl_hmac_channel_authenticator.cc
diff --git a/remoting/protocol/ssl_hmac_channel_authenticator.cc b/remoting/protocol/ssl_hmac_channel_authenticator.cc
index 0fba84965f97b4e7ab18009f64ba46dc700b6e9c..8fbdb290ce271911e770271663655bda9cb77e75 100644
--- a/remoting/protocol/ssl_hmac_channel_authenticator.cc
+++ b/remoting/protocol/ssl_hmac_channel_authenticator.cc
@@ -7,9 +7,9 @@
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "crypto/secure_util.h"
-#include "net/base/cert_verifier.h"
 #include "net/base/host_port_pair.h"
 #include "net/base/io_buffer.h"
+#include "net/base/multi_threaded_cert_verifier.h"
 #include "net/base/net_errors.h"
 #include "net/base/ssl_config_service.h"
 #include "net/base/x509_certificate.h"
@@ -86,7 +86,7 @@ void SslHmacChannelAuthenticator::SecureAndAuthenticate(
     result = server_socket->Handshake(base::Bind(
         &SslHmacChannelAuthenticator::OnConnected, base::Unretained(this)));
   } else {
-    cert_verifier_.reset(new net::CertVerifier());
+    cert_verifier_.reset(new net::MultiThreadedCertVerifier());
 
     net::SSLConfig::CertAndStatus cert_and_status;
     cert_and_status.cert_status = net::CERT_STATUS_AUTHORITY_INVALID;