Re-write many calls to WrapUnique() with MakeUnique()

ios/chrome/browser/signin/signin_client_factory.cc

 // Copyright 2015 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 "ios/chrome/browser/signin/signin_client_factory.h"
 
 #include "base/memory/ptr_util.h"
 #include "base/memory/singleton.h"
 #include "components/keyed_service/core/service_access_type.h"
 #include "components/keyed_service/ios/browser_state_dependency_manager.h"
@@ skipping 19 matching lines @@
           BrowserStateDependencyManager::GetInstance()) {
   DependsOn(ios::SigninErrorControllerFactory::GetInstance());
 }
 
 SigninClientFactory::~SigninClientFactory() {}
 
 std::unique_ptr<KeyedService> SigninClientFactory::BuildServiceInstanceFor(
     web::BrowserState* context) const {
   ios::ChromeBrowserState* chrome_browser_state =
       ios::ChromeBrowserState::FromBrowserState(context);
-  return base::WrapUnique(new SigninClientImpl(
+  return base::MakeUnique<SigninClientImpl>(
       chrome_browser_state,
       ios::SigninErrorControllerFactory::GetForBrowserState(
-          chrome_browser_state)));
+          chrome_browser_state));
 }