[Extensions] Remove ExtensionFunction::SetError()

extensions/browser/extension_function.cc

 // Copyright 2013 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 "extensions/browser/extension_function.h"
 
 #include <utility>
 
 #include "base/logging.h"
 #include "base/macros.h"
@@ skipping 294 matching lines @@
 }
 
 const base::ListValue* ExtensionFunction::GetResultList() const {
   return results_.get();
 }
 
 const std::string& ExtensionFunction::GetError() const {
   return error_;
 }
 
-void ExtensionFunction::SetError(const std::string& error) {
-  error_ = error;
-}
-
 bool ExtensionFunction::user_gesture() const {
   return user_gesture_ || UserGestureForTests::GetInstance()->HaveGesture();
 }
 
 ExtensionFunction::ResponseValue ExtensionFunction::NoArguments() {
   return ResponseValue(
       new ArgumentListResponseValue(this, base::MakeUnique<base::ListValue>()));
 }
 
 ExtensionFunction::ResponseValue ExtensionFunction::OneArgument(
@@ skipping 288 matching lines @@
 void AsyncExtensionFunction::SendResponse(bool success) {
   ResponseValue response;
   if (success) {
     response = ArgumentList(std::move(results_));
   } else {
     response = results_ ? ErrorWithArguments(std::move(results_), error_)
                         : Error(error_);
   }
   Respond(std::move(response));
 }