Replace c/b/nss_context by a KeyedService.

components/cert_database/cert_database_service_io_part_linux.h

+// Copyright 2014 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 COMPONENTS_CERT_DATABASE_PUBLIC_LINUX_CERT_DATABASE_SERVICE_IO_PART_LINUX_H_
+#define COMPONENTS_CERT_DATABASE_PUBLIC_LINUX_CERT_DATABASE_SERVICE_IO_PART_LINUX_H_
+
+#include "base/macros.h"
+#include "components/cert_database/cert_database_service_io_part.h"
+
+namespace cert_database {
+
+class CertDatabaseServiceIOPartLinux : public CertDatabaseServiceIOPart {
+ public:
+  CertDatabaseServiceIOPartLinux();
+  ~CertDatabaseServiceIOPartLinux() override;
+
+  void Init() override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(CertDatabaseServiceIOPartLinux);
+};
+
+}  // namespace cert_database
+
+#endif  // COMPONENTS_CERT_DATABASE_PUBLIC_LINUX_CERT_DATABASE_SERVICE_IO_PART_LINUX_H_