Use CertificateReportSender error callback to record HPKP UMA metrics

net/url_request/url_request_unittest.cc

Index: net/url_request/url_request_unittest.cc
diff --git a/net/url_request/url_request_unittest.cc b/net/url_request/url_request_unittest.cc
index 5c82c9a08cc79d6259c2f2d955104bc4b518008c..84ad5a044bf689f1200f4ffeda9a4952dbd2bc70 100644
--- a/net/url_request/url_request_unittest.cc
+++ b/net/url_request/url_request_unittest.cc
@@ -689,6 +689,9 @@ class MockCertificateReportSender
     latest_report_ = report;
   }
 
+  void SetErrorCallback(
+      const base::Callback<void(const GURL&, int)>& error_callback) override {}
+
   const GURL& latest_report_uri() { return latest_report_uri_; }
   const std::string& latest_report() { return latest_report_; }