Add optional context for certificate errors.

net/cert/internal/cert_error_scoper.cc

Index: net/cert/internal/cert_error_scoper.cc
diff --git a/net/cert/internal/cert_error_scoper.cc b/net/cert/internal/cert_error_scoper.cc
new file mode 100644
index 0000000000000000000000000000000000000000..c970f9acde6edf40bd0b4e13e781c68cc817367a
--- /dev/null
+++ b/net/cert/internal/cert_error_scoper.cc
@@ -0,0 +1,54 @@
+// 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.
+
+#include "net/cert/internal/cert_error_scoper.h"
+
+#include <memory>
+
+#include "base/logging.h"
+#include "base/memory/ptr_util.h"
+#include "net/cert/internal/cert_error_params.h"
+#include "net/cert/internal/cert_errors.h"
+
+namespace net {
+
+CertErrorScoper::CertErrorScoper(CertErrors* parent_errors) {
+  DCHECK(parent_errors);
+  parent_errors_ = parent_errors;
+  parent_scoper_ = parent_errors->SetScoper(this);
+}
+
+CertErrorScoper::~CertErrorScoper() {
+  CertErrorScoper* prev = parent_errors_->SetScoper(parent_scoper_);
+  DCHECK_EQ(prev, this);
+}
+
+CertErrorNode* CertErrorScoper::LazyGetRootNode() {
+  if (!root_node_) {
+    // Create the node.
+    auto root_node = BuildRootNode();
+    root_node_ = root_node.get();
+
+    // Attach it to the node hiearchy (ownership of this node is passed off
+    // to its parent, which is ultimately rooted in the CertErrors object).
+    if (parent_scoper_) {
+      parent_scoper_->LazyGetRootNode()->AddChild(std::move(root_node));
+    } else {
+      parent_errors_->nodes_.push_back(std::move(root_node));
+    }
+  }
+
+  return root_node_;
+}
+
+CertErrorScoperNoParams::CertErrorScoperNoParams(CertErrors* parent_errors,
+                                                 CertErrorId id)
+    : CertErrorScoper(parent_errors), id_(id) {}
+
+std::unique_ptr<CertErrorNode> CertErrorScoperNoParams::BuildRootNode() {
+  return base::MakeUnique<CertErrorNode>(CertErrorNodeType::TYPE_CONTEXT, id_,
+                                         nullptr);
+}
+
+}  // namespace net