Modifies BlockCleanupTest so that it can be used from ARC code.

ios/chrome/test/block_cleanup_test.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.
 
 #import <Foundation/Foundation.h>
 
 #import "ios/chrome/test/block_cleanup_test.h"
 
 #include "base/logging.h"
 #import "base/mac/scoped_nsobject.h"
+#import "base/mac/foundation_util.h"
 
 void BlockCleanupTest::SetUp() {
   block_cleanup_pool_ = [[NSAutoreleasePool alloc] init];
 }
 
 void BlockCleanupTest::TearDown() {
   // Block-copied items are released asynchronously; spin the loop to give them
   // a chance to be cleaned up.
   const NSTimeInterval kCleanupTime = 0.1;
   SpinRunLoop(kCleanupTime);
 
   // Drain the autorelease pool to finish cleaning up after blocks.
   // TODO(rohitrao): Can this be an EXPECT, so as to not crash the whole suite?
   DCHECK(block_cleanup_pool_);
-  [block_cleanup_pool_ release];
+  [base::mac::ObjCCastStrict<NSAutoreleasePool>(block_cleanup_pool_) release];
   block_cleanup_pool_ = nil;
 
   PlatformTest::TearDown();
 }
 
 void BlockCleanupTest::SpinRunLoop(NSTimeInterval cleanup_time) {
   NSDate* cleanup_start = [NSDate date];
   while (fabs([cleanup_start timeIntervalSinceNow]) < cleanup_time) {
     base::scoped_nsobject<NSDate> beforeDate(
         [[NSDate alloc] initWithTimeIntervalSinceNow:cleanup_time]);
     [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode
                              beforeDate:beforeDate];
   }
 }