Change virtual to override in devtools generator code.

content/browser/devtools/protocol/devtools_protocol_handler_generator.py

 #!/usr/bin/env python
 # 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.
 
 import sys
 import string
 import json
 
 blink_protocol_path = sys.argv[1]
@@ skipping 189 matching lines @@
 namespace ${domain} {
 class ${Domain}Handler;
 }  // namespace domain
 """)
 
 tmpl_client = string.Template("""\
 namespace ${domain} {
 class Client : public DevToolsProtocolClient {
  public:
   explicit Client(const RawMessageCallback& raw_message_callback);
-  virtual ~Client();
+  ~Client() override;
 
 ${methods}\
 };
 }  // namespace ${domain}
 """)
 
 tmpl_event = string.Template("""\
   void ${Command}(
       scoped_refptr<${Command}Params> params);
 """)
@@ skipping 572 matching lines @@
 output_h_file.close()
 
 output_cc_file.write(template_cc.substitute({},
     major = blink_protocol["version"]["major"],
     minor = blink_protocol["version"]["minor"],
     includes = "".join(sorted(includes)),
     fields_init = ",\n      ".join(fields_init),
     methods = "\n".join(handler_method_impls),
     types = "\n".join(type_impls)))
 output_cc_file.close()