Add optional context for certificate errors.

net/cert/internal/cert_error_scoper.h

Index: net/cert/internal/cert_error_scoper.h
diff --git a/net/cert/internal/cert_error_scoper.h b/net/cert/internal/cert_error_scoper.h
new file mode 100644
index 0000000000000000000000000000000000000000..141581270df1d1df00f4db9f146015f0b486753e
--- /dev/null
+++ b/net/cert/internal/cert_error_scoper.h
@@ -0,0 +1,59 @@
+// Copyright 2016 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_CERT_INTERNAL_CERT_ERROR_SCOPER_H_
+#define NET_CERT_INTERNAL_CERT_ERROR_SCOPER_H_
+
+#include <memory>
+
+#include "base/compiler_specific.h"
+#include "base/macros.h"
+#include "net/base/net_export.h"
+#include "net/cert/internal/cert_error_id.h"
+
+namespace net {
+
+class CertErrors;
+struct CertErrorNode;
+
+// CertErrorScoper is a base class for adding parent nodes into a CertErrors
+// object.
+class NET_EXPORT CertErrorScoper {
+ public:
+  explicit CertErrorScoper(CertErrors* parent_errors);
+  virtual ~CertErrorScoper();
+
+  // BuildRootNode() will be called at most once, to create the desired parent
+  // node. It may never be called if no errors are added to the CertErrors
+  // parent.
+  virtual std::unique_ptr<CertErrorNode> BuildRootNode() = 0;
+
+  // Returns the parent node for this scoper (the one created by
+  // BuildRootNode()).
+  CertErrorNode* LazyGetRootNode();
+
+ private:
+  CertErrorScoper* parent_scoper_ = nullptr;
+  CertErrors* parent_errors_ = nullptr;
+  CertErrorNode* root_node_ = nullptr;
+
+  DISALLOW_COPY_AND_ASSIGN(CertErrorScoper);
+};
+
+// Implementation of CertErrorScoper that creates a simple parent node with no
+// parameters (just an ID).
+class NET_EXPORT CertErrorScoperNoParams : public CertErrorScoper {
+ public:
+  CertErrorScoperNoParams(CertErrors* parent_errors, CertErrorId id);
+  std::unique_ptr<CertErrorNode> BuildRootNode() override;
+
+ private:
+  CertErrorId id_;
+
+  DISALLOW_COPY_AND_ASSIGN(CertErrorScoperNoParams);
+};
+
+}  // namespace net
+
+#endif  // NET_CERT_INTERNAL_CERT_ERROR_SCOPER_H_