APISignature::ParseArgumentsToJSON signature change.

The method now returns a struct instrad of having mutliple out params.

Chromium change:

https://chromium.googlesource.com/chromium/src/+/4ed01619c8ae43d3a1ef1f8acd713aa6aaa3530b

commit 4ed01619c8ae43d3a1ef1f8acd713aa6aaa3530b
Author: Devlin Cronin <rdevlin.cronin@chromium.org>
Date:   Thu Jul 18 17:41:55 2019 +0000

    [Extensions Bindings] Return a struct from APISignature parsing methods

    Make APISignature::ParseArgumentsToJSON(),
    APISignature::ParseArgumentsToV8(), and
    APISignature::ConvertArgumentsIgnoringSchema() return a struct
    containing the parse results, including arguments, error, and
    async response type (callback if one were provided).

    This will make it easier when we need to provide additional information
    about if a promise should be returned.

    No behavior change is expected.

    Bug: 978538

extensions/renderer/brave_shields_content_setting.cc

@@ -120,15 +120,12 @@ void BraveShieldsContentSetting::HandleFunction(const std::string& method_name,
   if (!access_checker_->HasAccessOrThrowError(context, full_name))
     return;
 
-  std::unique_ptr<base::ListValue> converted_arguments;
-  v8::Local<v8::Function> callback;
-  std::string error;
   const APISignature* signature = type_refs_->GetTypeMethodSignature(full_name);
-  if (!signature->ParseArgumentsToJSON(context, argument_list, *type_refs_,
-                                       &converted_arguments, &callback,
-                                       &error)) {
+  APISignature::JSONParseResult parse_result =
+      signature->ParseArgumentsToJSON(context, argument_list, *type_refs_);
+  if (!parse_result.succeeded()) {
     arguments->ThrowTypeError(api_errors::InvocationError(
-        full_name, signature->GetExpectedSignature(), error));
+        full_name, signature->GetExpectedSignature(), *parse_result.error));
     return;
   }
 
@@ -148,10 +145,11 @@ void BraveShieldsContentSetting::HandleFunction(const std::string& method_name,
     }
   }
 
-  converted_arguments->Insert(0u, std::make_unique<base::Value>(pref_name_));
+  parse_result.arguments->Insert(0u, std::make_unique<base::Value>(pref_name_));
   request_handler_->StartRequest(
-      context, "braveShields." + method_name, std::move(converted_arguments),
-      callback, v8::Local<v8::Function>(), binding::RequestThread::UI);
+      context, "braveShields." + method_name, std::move(parse_result.arguments),
+      parse_result.callback, v8::Local<v8::Function>(),
+      binding::RequestThread::UI); 
 }
 
 }  // namespace extensions