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

chrome/browser/cocoa/cookies_window_controller.h

Index: chrome/browser/cocoa/cookies_window_controller.h
diff --git a/chrome/browser/cocoa/cookies_window_controller.h b/chrome/browser/cocoa/cookies_window_controller.h
index 18e4434064cea566dfa72b1a91edb84cfb987eb6..fac226ab80eafd462564f02492eb35428fdd30cd 100644
--- a/chrome/browser/cocoa/cookies_window_controller.h
+++ b/chrome/browser/cocoa/cookies_window_controller.h
@@ -81,10 +81,14 @@ class CookiesTreeModelObserverBridge : public TreeModelObserver {
   // 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.