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

ios/chrome/browser/browsing_data/browsing_data_removal_controller_unittest.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/browsing_data/browsing_data_removal_controller.h"
 
 #include <memory>
 
-#import "base/mac/scoped_nsobject.h"
 #import "base/test/ios/wait_util.h"
 #include "ios/chrome/browser/browser_state/test_chrome_browser_state.h"
 #include "ios/web/public/test/web_test.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #import "third_party/ocmock/OCMock/OCMock.h"
 #import "third_party/ocmock/gtest_support.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 typedef web::WebTest BrowsingDataRemovalControllerTest;
 
 // Tests that |removeIOSSpecificIncognitoBrowsingDataFromBrowserState:| can
 // finish performing its operation even when a BrowserState is destroyed.
 TEST_F(BrowsingDataRemovalControllerTest, PerformAfterBrowserStateDestruction) {
   __block BOOL block_was_called = NO;
   id mock_delegate = [OCMockObject
       mockForProtocol:@protocol(BrowsingDataRemovalControllerDelegate)];
-  base::scoped_nsobject<BrowsingDataRemovalController> removal_controller(
-      [[BrowsingDataRemovalController alloc] initWithDelegate:mock_delegate]);
+  BrowsingDataRemovalController* removal_controller =
+      [[BrowsingDataRemovalController alloc] initWithDelegate:mock_delegate];
 
   TestChromeBrowserState::Builder builder;
   std::unique_ptr<TestChromeBrowserState> browser_state = builder.Build();
   ios::ChromeBrowserState* otr_browser_state =
       browser_state->GetOffTheRecordChromeBrowserState();
   int remove_all_mask = ~0;
   [removal_controller
       removeIOSSpecificIncognitoBrowsingDataFromBrowserState:otr_browser_state
                                                         mask:remove_all_mask
                                            completionHandler:^{
                                              block_was_called = YES;
                                            }];
   // Destroy the BrowserState immediately.
   browser_state->DestroyOffTheRecordChromeBrowserState();
 
   base::test::ios::WaitUntilCondition(^bool() {
     return block_was_called;
   });
 }