Factor iOS native image loading into a utility function.

ios/chrome/browser/ui/tab_switcher/tab_switcher_utils.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.
 
 #import "ios/chrome/browser/ui/tab_switcher/tab_switcher_utils.h"
 
 #import <UIKit/UIKit.h>
 
 #include "base/logging.h"
 #include "base/mac/scoped_nsobject.h"
 #include "components/browser_sync/profile_sync_service.h"
 #include "components/sync/driver/sync_service.h"
 #include "components/sync_sessions/open_tabs_ui_delegate.h"
 #include "ios/chrome/browser/browser_state/chrome_browser_state.h"
 #import "ios/chrome/browser/favicon/favicon_loader.h"
 #include "ios/chrome/browser/favicon/ios_chrome_favicon_loader_factory.h"
 #include "ios/chrome/browser/sync/ios_chrome_profile_sync_service_factory.h"
+#import "ios/chrome/browser/ui/uikit_ui_util.h"
 #include "ios/chrome/grit/ios_theme_resources.h"
-#include "ui/base/resource/resource_bundle.h"
 
 namespace ios_internal {
 
 UIImage* DefaultFaviconImage() {
-  ResourceBundle& rb = ResourceBundle::GetSharedInstance();
-  return rb.GetNativeImageNamed(IDR_IOS_OMNIBOX_HTTP).ToUIImage();
+  return NativeImage(IDR_IOS_OMNIBOX_HTTP);
 }
 
 void GetFavicon(GURL const& url,
                 ios::ChromeBrowserState* browser_state,
                 ios_internal::FaviconGetterCompletionBlock block) {
   DCHECK(browser_state);
   syncer::SyncService* sync_service =
       IOSChromeProfileSyncServiceFactory::GetForBrowserState(browser_state);
   sync_sessions::OpenTabsUIDelegate* open_tabs =
       sync_service ? sync_service->GetOpenTabsUIDelegate() : NULL;
@@ skipping 145 matching lines @@
 
   // The backtracking results in the indexes of the operations being stored in
   // decreasing order.
   // For readability, order them in ascending value.
   std::reverse(std::begin(*substitutions), std::end(*substitutions));
   std::reverse(std::begin(*deletions), std::end(*deletions));
   std::reverse(std::begin(*insertions), std::end(*insertions));
 }
 
 }  // namespace ios_internal