Add security handler stub for sending the lock icon status to DevTools.

content/browser/devtools/protocol/security_handler.cc

+// Copyright 2015 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 "content/browser/devtools/protocol/security_handler.h"
+
+namespace content {
+namespace devtools {
+namespace security {
+
+typedef DevToolsProtocolClient::Response Response;
+
+SecurityHandler::SecurityHandler() {
+}
+
+SecurityHandler::~SecurityHandler() {
+}
+
+void SecurityHandler::SetClient(scoped_ptr<DevToolsProtocolClient> client) {
+}
+
+Response SecurityHandler::Enable() {
+  return Response::OK();
+}
+
+Response SecurityHandler::Disable() {
+  return Response::OK();
+}
+
+}  // namespace security
+}  // namespace devtools
+}  // namespace content