Add --ignore-certificate-errors-spki-list switch and UMA histogram.

chrome/browser/ssl/ignore_errors_cert_verifier.h

+// Copyright (c) 2017 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 CHROME_BROWSER_SSL_IGNORE_ERRORS_CERT_VERIFIER_H_
+#define CHROME_BROWSER_SSL_IGNORE_ERRORS_CERT_VERIFIER_H_
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "base/containers/flat_set.h"
+#include "net/cert/cert_verifier.h"
+
+namespace net {
+struct SHA256HashValue;
+class SHA256HashValueLessThan;
+}  // namespace net
+
+// IgnoreErrorsCertVerifier wraps another CertVerifier in order to ignore
+// verification errors from certificate chains that match a whitelist of SPKI
+// fingerprints.
+class NET_EXPORT IgnoreErrorsCertVerifier : public net::CertVerifier {
+ public:
+  // SPKIHashSet is a set of SHA-256 SPKI fingerprints (RFC 7469, Section 2.4).
+  using SPKIHashSet =
+      base::flat_set<net::SHA256HashValue, net::SHA256HashValueLessThan>;
+
+  // MakeWhitelist converts a vector of Base64-encoded SHA-256 SPKI fingerprints
+  // into an SPKIHashSet. Invalid fingerprints are logged and skipped.
+  static SPKIHashSet MakeWhitelist(
+      const std::vector<std::string>& fingerprints);
+
+  IgnoreErrorsCertVerifier(std::unique_ptr<net::CertVerifier> verifier,
+                           SPKIHashSet whitelist);
+
+  ~IgnoreErrorsCertVerifier() override;
+
+  // Verify invokes Verify() on the wrapped CertVerifier. If any of the
+  // certificates from the chain in |params| match one of the SPKI fingerprints
+  // from the whitelist, it returns OK regardless of the actual verification
+  // result (or ERR_IO_PENDING on asynchronous completion). Otherwise the actual
+  // result is returned.

[Ryan Sleevi, 2017/04/25 18:07:09]

I think this needs updating with the new behaviour?

[martinkr, 2017/04/25 19:48:37]

Done.

+  int Verify(const RequestParams& params,
+             net::CRLSet* crl_set,
+             net::CertVerifyResult* verify_result,
+             const net::CompletionCallback& callback,
+             std::unique_ptr<Request>* out_req,
+             const net::NetLogWithSource& net_log) override;
+
+ private:
+  std::unique_ptr<net::CertVerifier> verifier_;
+  SPKIHashSet whitelist_;
+};
+
+#endif  // CHROME_BROWSER_SSL_IGNORE_ERRORS_CERT_VERIFIER_H_