Removing 'AllowScopedIO' exception from SecurityKeyAuthHandlerLinux

remoting/host/security_key/security_key_extension.h

 // 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 REMOTING_HOST_SECURITY_KEY_SECURITY_KEY_EXTENSION_H_
 #define REMOTING_HOST_SECURITY_KEY_SECURITY_KEY_EXTENSION_H_
 
 #include <memory>
 #include <string>
 
 #include "base/macros.h"
+#include "base/memory/ref_counted.h"
 #include "remoting/host/host_extension.h"
 
+namespace base {
+class SingleThreadTaskRunner;
+}  // namespace base
+
 namespace remoting {
 
 class ClientSessionDetails;
 class HostExtensionSession;
 
 // SecurityKeyExtension extends HostExtension to enable Security Key support.
 class SecurityKeyExtension : public HostExtension {
  public:
-  SecurityKeyExtension();
+  explicit SecurityKeyExtension(
+      scoped_refptr<base::SingleThreadTaskRunner> file_task_runner);
   ~SecurityKeyExtension() override;
 
   // HostExtension interface.
   std::string capability() const override;
   std::unique_ptr<HostExtensionSession> CreateExtensionSession(
       ClientSessionDetails* client_session_details,
       protocol::ClientStub* client_stub) override;
 
  private:
+  // Allows underlying auth handler to perform blocking file IO.
+  scoped_refptr<base::SingleThreadTaskRunner> file_task_runner_;
+
   DISALLOW_COPY_AND_ASSIGN(SecurityKeyExtension);
 };
 
 }  // namespace remoting
 
 #endif  // REMOTING_HOST_SECURITY_KEY_SECURITY_KEY_EXTENSION_H_