Make CertVerifier a pure virtual interface.

net/proxy/proxy_script_fetcher_impl_unittest.cc

Index: net/proxy/proxy_script_fetcher_impl_unittest.cc
diff --git a/net/proxy/proxy_script_fetcher_impl_unittest.cc b/net/proxy/proxy_script_fetcher_impl_unittest.cc
index d29dcba23ce7fa8688b7b05d2213654261bc4e86..393eca32342cffda953541cd5dc03b2e9203dfd6 100644
--- a/net/proxy/proxy_script_fetcher_impl_unittest.cc
+++ b/net/proxy/proxy_script_fetcher_impl_unittest.cc
@@ -12,6 +12,7 @@
 #include "base/utf_string_conversions.h"
 #include "net/base/net_util.h"
 #include "net/base/load_flags.h"
+#include "net/base/multi_threaded_cert_verifier.h"
 #include "net/base/ssl_config_service_defaults.h"
 #include "net/base/test_completion_callback.h"
 #include "net/disk_cache/disk_cache.h"
@@ -72,7 +73,7 @@ class RequestContext : public URLRequestContext {
         CreateSystemHostResolver(HostResolver::kDefaultParallelism,
                                  HostResolver::kDefaultRetryAttempts,
                                  NULL));
-    storage_.set_cert_verifier(new CertVerifier);
+    storage_.set_cert_verifier(new MultiThreadedCertVerifier);
     storage_.set_proxy_service(ProxyService::CreateFixed(no_proxy));
     storage_.set_ssl_config_service(new SSLConfigServiceDefaults);
     storage_.set_http_server_properties(new HttpServerPropertiesImpl);