[Mac] Implement NSObject zombies.

chrome/browser/cocoa/objc_zombie.h

+// Copyright (c) 2010 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.
+
+#ifndef CHROME_BROWSER_COCOA_NSOBJECT_ZOMBIE_H_
+#define CHROME_BROWSER_COCOA_NSOBJECT_ZOMBIE_H_
+
+#import <Foundation/Foundation.h>
+
+// You should think twice every single time you use anything from this
+// namespace.
+namespace ObjcEvilDoers {
+
+// Enable zombies.  Returns NO if it fails to enable.
+//
+// When |zombieAllObjects| is YES, all objects inheriting from
+// NSObject become zombies on -dealloc.  If NO, -shouldBecomeCrZombie
+// is queried to determine whether to make the object a zombie.
+//
+// |zombieCount| controls how many zombies to store before freeing the
+// oldest.  Set to 0 to free objects immediately after making them
+// zombies.
+BOOL ZombieEnable(BOOL zombieAllObjects, size_t zombieCount);
+
+// Disable zombies.
+void ZombieDisable();
+
+}  // namespace ObjcEvilDoers
+
+@interface NSObject (CrZombie)
+- (BOOL)shouldBecomeCrZombie;
+@end
+
+#endif  // CHROME_BROWSER_COCOA_NSOBJECT_ZOMBIE_H_