Enabled pressing TAB to cycle through the Omnibox results.

chrome/browser/ui/cocoa/omnibox/omnibox_popup_view_mac.mm

 // Copyright (c) 2011 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 "chrome/browser/ui/cocoa/omnibox/omnibox_popup_view_mac.h"
 
 #include <cmath>
 
 #include "base/stl_util.h"
 #include "base/sys_string_conversions.h"
@@ skipping 529 matching lines @@
   if (!force_background) {
     disposition =
         event_utils::WindowOpenDispositionFromNSEvent([NSApp currentEvent]);
   }
 
   // OpenMatch() may close the popup, which will clear the result set
   // and, by extension, |match| and its contents.  So copy the
   // relevant match out to make sure it stays alive until the call
   // completes.
   AutocompleteMatch match = model_->result().match_at(row);
-  string16 keyword;
-  const bool is_keyword_hint = model_->GetKeywordForMatch(match, &keyword);
   omnibox_view_->OpenMatch(match, disposition, GURL(), row,
-                           is_keyword_hint ? string16() : keyword);
+                           match.keyword);
 }
 
 void OmniboxPopupViewMac::UserPressedOptIn(bool opt_in) {
   PromoCounter* counter = profile_->GetInstantPromoCounter();
   DCHECK(counter);
   counter->Hide();
   if (opt_in) {
     browser::ShowInstantConfirmDialogIfNecessary([field_ window], profile_);
   }
 
@@ skipping 260 matching lines @@
                         bottomLeftCornerRadius:kPopupRoundingRadius
                        bottomRightCornerRadius:kPopupRoundingRadius];
 
   // Draw the matrix clipped to our border.
   gfx::ScopedNSGraphicsContextSaveGState scopedGState;
   [path addClip];
   [super drawRect:rect];
 }
 
 @end