[Mac] Move UI item validation to UserInterfaceItemCommandHandler.

chrome/browser/ui/cocoa/browser_window_controller.h

Index: chrome/browser/ui/cocoa/browser_window_controller.h
diff --git a/chrome/browser/ui/cocoa/browser_window_controller.h b/chrome/browser/ui/cocoa/browser_window_controller.h
index 60beb8bcc3ce0788c87027ba0c966be22e466781..3ffff489cedc0d802952a1cb6a48313ad980a9d3 100644
--- a/chrome/browser/ui/cocoa/browser_window_controller.h
+++ b/chrome/browser/ui/cocoa/browser_window_controller.h
@@ -57,11 +57,10 @@ namespace extensions {
 class Command;
 }
 
-@interface BrowserWindowController :
-  TabWindowController<NSUserInterfaceValidations,
-                      BookmarkBarControllerDelegate,
-                      ViewResizer,
-                      TabStripControllerDelegate> {
+@interface BrowserWindowController
+    : TabWindowController<BookmarkBarControllerDelegate,
+                          ViewResizer,
+                          TabStripControllerDelegate> {
  @private
   // The ordering of these members is important as it determines the order in
   // which they are destroyed. |browser_| needs to be destroyed last as most of