Convert //ios from scoped_ptr to std::unique_ptr.

ios/public/provider/web/web_controller_provider.mm

 // 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/public/provider/web/web_controller_provider.h"
 
 namespace ios {
 
 static WebControllerProviderFactory* g_web_controller_provider_factory;
 
@@ skipping 25 matching lines @@
   if (completion)
     completion(nil, nil);
 }
 
 WebControllerProviderFactory::WebControllerProviderFactory() {
 }
 
 WebControllerProviderFactory::~WebControllerProviderFactory() {
 }
 
-scoped_ptr<WebControllerProvider>
+std::unique_ptr<WebControllerProvider>
 WebControllerProviderFactory::CreateWebControllerProvider(
     web::BrowserState* browser_state) {
-  return scoped_ptr<WebControllerProvider>(
+  return std::unique_ptr<WebControllerProvider>(
       new WebControllerProvider(browser_state));
 }
 
 }  // namespace ios