[Mac] Fix a crash in the cookies manager that was caused by an invalid selection.

chrome/browser/cocoa/cookies_window_controller.h

 // Copyright (c) 2009 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 <Cocoa/Cocoa.h>
 
 #include "app/tree_model.h"
 #include "base/cocoa_protocols_mac.h"
 #include "base/scoped_nsobject.h"
 #include "base/scoped_ptr.h"
@@ skipping 63 matching lines @@
   // Platform-independent model and C++/Obj-C bridge components.
   scoped_ptr<CookiesTreeModel> treeModel_;
   scoped_ptr<CookiesTreeModelObserverBridge> modelObserver_;
 
   // Cached array of icons.
   scoped_nsobject<NSMutableArray> icons_;
 
   // Our Cocoa copy of the model.
   scoped_nsobject<CocoaCookieTreeNode> cocoaTreeModel_;
 
+  // A flag indicating whether or not the "Remove" button should be enabled.
+  BOOL removeButtonEnabled_;
+
   IBOutlet NSTreeController* treeController_;
 
   Profile* profile_;  // weak
 }
+@property (assign, nonatomic) BOOL removeButtonEnabled;
 @property (readonly, nonatomic) NSTreeController* treeController;
 
 // Designated initializer. Profile cannot be NULL.
 - (id)initWithProfile:(Profile*)profile;
 
 // Shows the cookies window as a modal sheet attached to |window|.
 - (void)attachSheetTo:(NSWindow*)window;
 
 // Delete cookie actions.
 - (IBAction)deleteCookie:(id)sender;
@@ skipping 10 matching lines @@
 - (CookiesTreeModel*)treeModel;
 
 @end
 
 @interface CookiesWindowController (UnitTesting)
 - (void)clearBrowsingDataNotification:(NSNotification*)notif;
 - (CookiesTreeModelObserverBridge*)modelObserver;
 - (NSArray*)icons;
 - (void)loadTreeModelFromProfile;
 @end