[inspector_protocol] Allow custom json parser.

templates/TypeBuilder_cpp.template

 // This file is generated
 
 // Copyright (c) 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.
 
 #include "{{config.protocol.package}}/{{domain.domain}}.h"
 
 #include "{{config.protocol.package}}/Protocol.h"
 
@@ skipping 88 matching lines @@
 {{config.exported.string_out}} {{type.id}}::toJSONString() const
 {
     String json = serialize()->toJSONString();
     return {{config.exported.to_string_out % "json"}};
 }
 
 // static
 std::unique_ptr<API::{{type.id}}> API::{{type.id}}::fromJSONString(const {{config.exported.string_in}}& json)
 {
     ErrorSupport errors;
-    std::unique_ptr<Value> value = parseJSON(json);
+    std::unique_ptr<Value> value = StringUtil::parseJSON(json);
     if (!value)
         return nullptr;
     return protocol::{{domain.domain}}::{{type.id}}::parse(value.get(), &errors);
 }
     {% endif %}
   {% endfor %}
 
 // ------------- Enum values from params.
 
   {% for command in join_arrays(domain, ["commands", "events"]) %}
@@ skipping 228 matching lines @@
         {%- if command.parameters -%}, {% endif -%}
         std::move(callback));
     return DispatchResponse::kAsync;
     {% endif %}
 }
   {% endfor %}
 
 // static
 void Dispatcher::wire(UberDispatcher* dispatcher, Backend* backend)
 {
-    dispatcher->registerBackend("{{domain.domain}}", wrapUnique(new DispatcherImpl(dispatcher->channel(), backend)));
+    dispatcher->registerBackend("{{domain.domain}}", std::unique_ptr<protocol::DispatcherBase>(new DispatcherImpl(dispatcher->channel(), backend)));
 }
 
 } // {{domain.domain}}
 {% for namespace in config.protocol.namespace %}
 } // namespace {{namespace}}
 {% endfor %}