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

ios/chrome/test/app/history_test_util.mm

 // Copyright 2016 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/test/app/history_test_util.h"
 
 #import "base/mac/bind_objc_block.h"
 #import "base/test/ios/wait_util.h"
 #include "components/browsing_data/core/browsing_data_utils.h"
 #import "ios/chrome/app/main_controller.h"
 #import "ios/chrome/app/main_controller_private.h"
 #include "ios/chrome/browser/browser_state/chrome_browser_state.h"
 #include "ios/chrome/browser/browsing_data/ios_chrome_browsing_data_remover.h"
 #include "ios/chrome/browser/callback_counter.h"
 #import "ios/chrome/test/app/chrome_test_util.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace chrome_test_util {
 
 void ClearBrowsingHistory() {
   MainController* main_controller = GetMainController();
   ios::ChromeBrowserState* active_state = GetOriginalBrowserState();
   scoped_refptr<CallbackCounter> callback_counter(
-      new CallbackCounter(base::BindBlock(^{
+      new CallbackCounter(base::BindBlockArc(^{
       })));
   callback_counter->IncrementCount();
   __block bool did_complete = false;
   [main_controller
       removeBrowsingDataFromBrowserState:active_state
                                     mask:IOSChromeBrowsingDataRemover::
                                              REMOVE_HISTORY
                               timePeriod:browsing_data::TimePeriod::ALL_TIME
                        completionHandler:^{
                          callback_counter->DecrementCount();
                          did_complete = true;
                        }];
   // TODO(crbug.com/631795): This is a workaround that will be removed soon.
   // This code waits for success or timeout, then returns. This needs to be
   // fixed so that failure is correctly marked here, or the caller handles
   // waiting for the operation to complete.
   // Wait for history to be cleared.
   NSDate* deadline = [NSDate dateWithTimeIntervalSinceNow:4.0];
   while (!did_complete &&
          [[NSDate date] compare:deadline] != NSOrderedDescending) {
     base::test::ios::SpinRunLoopWithMaxDelay(
         base::TimeDelta::FromSecondsD(0.1));
   }
 }
 
 }  // namespace chrome_test_util