Make CertVerifier a pure virtual interface.

net/http/http_network_layer_unittest.cc

Index: net/http/http_network_layer_unittest.cc
diff --git a/net/http/http_network_layer_unittest.cc b/net/http/http_network_layer_unittest.cc
index bdb777c0ad1fe0be22ebc0eab1014d3085897069..0aa7082989a33dd92c7d14649cfe20c7fd46a751 100644
--- a/net/http/http_network_layer_unittest.cc
+++ b/net/http/http_network_layer_unittest.cc
@@ -4,6 +4,7 @@
 
 #include "net/base/cert_verifier.h"
 #include "net/base/mock_host_resolver.h"
+#include "net/base/multi_threaded_cert_verifier.h"
 #include "net/base/net_log.h"
 #include "net/base/ssl_config_service_defaults.h"
 #include "net/http/http_network_layer.h"
@@ -38,7 +39,7 @@ class HttpNetworkLayerTest : public PlatformTest {
 
   MockClientSocketFactory mock_socket_factory_;
   MockHostResolver host_resolver_;
-  CertVerifier cert_verifier_;
+  MultiThreadedCertVerifier cert_verifier_;
   const scoped_ptr<ProxyService> proxy_service_;
   const scoped_refptr<SSLConfigService> ssl_config_service_;
   scoped_refptr<HttpNetworkSession> network_session_;