[inspector_protocol] support fall through and moveable Maybe

inspector_protocol.gypi

 # 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.
 
 {
   'variables': {
     'inspector_protocol_files': [
       'lib/Allocator_h.template',
       'lib/Array_h.template',
-      'lib/BackendCallback_h.template',
       'lib/Collections_h.template',
       'lib/DispatcherBase_cpp.template',
       'lib/DispatcherBase_h.template',
       'lib/ErrorSupport_cpp.template',
       'lib/ErrorSupport_h.template',
       'lib/Forward_h.template',
       'lib/FrontendChannel_h.template',
       'lib/Maybe_h.template',
       'lib/Object_cpp.template',
       'lib/Object_h.template',
       'lib/Parser_cpp.template',
       'lib/Parser_h.template',
       'lib/Protocol_cpp.template',
       'lib/ValueConversions_h.template',
       'lib/Values_cpp.template',
       'lib/Values_h.template',
       'templates/Exported_h.template',
       'templates/Imported_h.template',
       'templates/TypeBuilder_cpp.template',
       'templates/TypeBuilder_h.template',
       'CodeGenerator.py',
     ]
   }
 }