[ObjC ARC] Converts ios/chrome/app/startup:startup to ARC.

ios/chrome/app/startup/ios_chrome_main_delegate.mm

 // Copyright (c) 2012 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/app/startup/ios_chrome_main_delegate.h"
 
 #include "base/logging.h"
 #include "ios/chrome/browser/chrome_paths.h"
 #include "third_party/skia/include/core/SkGraphics.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 IOSChromeMainDelegate::IOSChromeMainDelegate() {}
 
 IOSChromeMainDelegate::~IOSChromeMainDelegate() {}
 
 void IOSChromeMainDelegate::BasicStartupComplete() {
   // Initialize Skia. On desktop this is made by content::BrowserMainRunnerImpl,
   // however web does not have a dependency on skia, so it is done as part of
   // Chrome initialisation on iOS.
   SkGraphics::Init();
 
   // Initialize the Chrome path provider.
   ios::RegisterPathProvider();
 
   // Upstream wires up log file handling here based on flags; for now that's
   // not supported, and this is called just to handle vlog levels and patterns.
   // If redirecting to a file is ever needed, add it here (see
   // logging_chrome.cc for example code).
   logging::LoggingSettings log_settings;
   logging::InitLogging(log_settings);
 }