Fix issue where cmd-w was hard-coded to closing a browser tab regardless of t...

chrome/browser/cocoa/browser_window_controller.mm

 // 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.
 
 #include "base/mac_util.h"
 #include "base/sys_string_conversions.h"
 #include "chrome/app/chrome_dll_resource.h"  // IDC_*
 #include "chrome/browser/browser.h"
 #include "chrome/browser/browser_list.h"
 #include "chrome/browser/browser_process.h"
@@ skipping 291 matching lines @@
 // too early to tell.
 - (BOOL)validateUserInterfaceItem:(id<NSValidatedUserInterfaceItem>)item {
   SEL action = [item action];
   BOOL enable = NO;
   if (action == @selector(commandDispatch:)) {
     NSInteger tag = [item tag];
     if (browser_->command_updater()->SupportsCommand(tag)) {
       // Generate return value (enabled state)
       enable = browser_->command_updater()->IsCommandEnabled(tag) ? YES : NO;
 
+      // Disable "close tab" if we're not the key window or if there's only
+      // one tab.
+      if (tag == IDC_CLOSE_TAB)
+        enable &= [self numberOfTabs] > 1 && [[self window] isKeyWindow];
+
       // If the item is toggleable, find it's toggle state and
       // try to update it.  This is a little awkward, but the alternative is
       // to check after a commandDispatch, which seems worse.
       [self updateToggleStateWithTag:tag forItem:item];
     }
   }
   return enable;
 }
 
 // Called when the user picks a menu or toolbar item when this window is key.
@@ skipping 365 matching lines @@
   else if ([event deltaY] < -0.5)
     ;  // TODO(pinkerton): figure out page-down
 
   // Ensure the command is valid first (ExecuteCommand() won't do that) and
   // then make it so.
   if (browser_->command_updater()->IsCommandEnabled(command))
     browser_->ExecuteCommand(command);
 }
 
 @end