Added the "Show as Tab" option for popups on OSX

chrome/browser/app_controller_mac.mm

 // Copyright (c) 2012 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 "chrome/browser/app_controller_mac.h"
 
 #include <stddef.h>
 
 #include "base/auto_reset.h"
 #include "base/bind.h"
@@ skipping 964 matching lines @@
 #if defined(GOOGLE_CHROME_BUILD)
         case IDC_FEEDBACK:
           enable = NO;
           break;
 #endif
         default:
           enable = menuState_->IsCommandEnabled(tag) ?
                    ![self keyWindowIsModal] : NO;
       }
     }
+
+    // "Show as tab" should only appear when the current window is a popup.
+    // Since |validateUserInterfaceItem:| is called only when there are no
+    // key windows, we should just hide this.
+    // This is handled outside of the switch statement because we want to hide
+    // this regardless if the command is supported or not.
+    if (tag == IDC_SHOW_AS_TAB) {
+      NSMenuItem* menuItem = base::mac::ObjCCast<NSMenuItem>(item);
+      [menuItem setHidden:YES];
+    }
   } else if (action == @selector(terminate:)) {
     enable = YES;
   } else if (action == @selector(showPreferences:)) {
     enable = YES;
   } else if (action == @selector(orderFrontStandardAboutPanel:)) {
     enable = YES;
   } else if (action == @selector(commandFromDock:)) {
     enable = YES;
   } else if (action == @selector(toggleConfirmToQuit:)) {
     [self updateConfirmToQuitPrefMenuItem:static_cast<NSMenuItem*>(item)];
@@ skipping 700 matching lines @@
 
 //---------------------------------------------------------------------------
 
 namespace app_controller_mac {
 
 bool IsOpeningNewWindow() {
   return g_is_opening_new_window;
 }
 
 }  // namespace app_controller_mac