[ObjC ARC] Converts ios/chrome/browser/ui/bookmarks:unit_tests to ARC.

ios/chrome/browser/ui/bookmarks/bookmark_home_view_controller_unittest.mm

 // 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 "base/mac/scoped_nsobject.h"
 #include "components/bookmarks/browser/bookmark_model.h"
 #import "ios/chrome/browser/browser_state/test_chrome_browser_state.h"
 #import "ios/chrome/browser/ui/bookmarks/bookmark_home_handset_view_controller.h"
 #include "ios/chrome/browser/ui/bookmarks/bookmark_ios_unittest.h"
 #import "ios/chrome/browser/ui/bookmarks/bookmark_promo_controller.h"
 #import "ios/chrome/browser/ui/bookmarks/bookmark_utils_ios.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 using bookmarks::BookmarkNode;
 
 // A partial mock subclass that doesn't load any heavy weight subclasses.
 @interface MockBookmarkHomeHandsetViewController
     : BookmarkHomeHandsetViewController
 @end
 
 @implementation MockBookmarkHomeHandsetViewController
 
 - (void)hideEditingBarAnimated:(BOOL)animated {
@@ skipping 29 matching lines @@
     AddBookmark(f1, @"f1c");
     const BookmarkNode* f2a = AddBookmark(f2, @"f2a");
     AddBookmark(f2, @"f2b");
 
     std::set<const BookmarkNode*> toDelete;
     toDelete.insert(b);
     toDelete.insert(f1a);
     toDelete.insert(f1);
     toDelete.insert(f2a);
 
-    base::scoped_nsobject<MockBookmarkHomeHandsetViewController> controller(
+    MockBookmarkHomeHandsetViewController* controller =
         [[MockBookmarkHomeHandsetViewController alloc]
             initWithLoader:nil
-              browserState:chrome_browser_state_.get()]);
+              browserState:chrome_browser_state_.get()];
 
     [controller resetEditNodes];
     [controller insertEditNode:f1 atIndexPath:nil];
     [controller insertEditNode:a atIndexPath:nil];
     [controller insertEditNode:f2 atIndexPath:nil];
 
     bookmark_utils_ios::DeleteBookmarks(toDelete, _bookmarkModel);
 
     // After the deletion, only 'a' and 'f2' should be left.
     std::set<const BookmarkNode*> editingNodes = [controller editNodes];
     EXPECT_EQ(editingNodes.size(), 2u);
     EXPECT_TRUE(editingNodes.find(a) != editingNodes.end());
     EXPECT_TRUE(editingNodes.find(f2) != editingNodes.end());
   }
 }
 
 }  // anonymous namespace