Use CertificateReportSender error callback to record HPKP UMA metrics

net/http/transport_security_state.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NET_HTTP_TRANSPORT_SECURITY_STATE_H_
 #define NET_HTTP_TRANSPORT_SECURITY_STATE_H_
 
 #include <stdint.h>
 
 #include <map>
 #include <string>
 #include <utility>
 #include <vector>
 
+#include "base/callback.h"
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/threading/non_thread_safe.h"
 #include "base/time/time.h"
 #include "net/base/expiring_cache.h"
 #include "net/base/net_export.h"
 #include "net/cert/x509_cert_types.h"
 #include "net/cert/x509_certificate.h"
 #include "url/gurl.h"
 
@@ skipping 171 matching lines @@
     // provided.
     GURL report_uri;
   };
 
   // An interface for asynchronously sending HPKP violation reports.
   class NET_EXPORT ReportSender {
    public:
     // Sends the given serialized |report| to |report_uri|.
     virtual void Send(const GURL& report_uri, const std::string& report) = 0;
 
+    // Sets a callback to be called when report sending fails.
+    virtual void SetErrorCallback(
+        const base::Callback<void(GURL, int)>& error_callback) = 0;

[eroman, 2016/04/02 01:55:25]

why not a const GURL?

[estark, 2016/04/05 00:57:29]

Done.

+
    protected:
     virtual ~ReportSender() {}
   };
 
   // An interface for building and asynchronously sending reports when a
   // site expects valid Certificate Transparency information but it
   // wasn't supplied.
   class NET_EXPORT ExpectCTReporter {
    public:
     // Called when the host in |host_port_pair| has opted in to have
@@ skipping 253 matching lines @@
   // rate-limiting.
   ExpiringCache<std::string, bool, base::TimeTicks, std::less<base::TimeTicks>>
       sent_reports_cache_;
 
   DISALLOW_COPY_AND_ASSIGN(TransportSecurityState);
 };
 
 }  // namespace net
 
 #endif  // NET_HTTP_TRANSPORT_SECURITY_STATE_H_