Enabled pressing TAB to cycle through the Omnibox results.

chrome/browser/ui/cocoa/omnibox/omnibox_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_view_mac.h"
 
 #include <Carbon/Carbon.h>  // kVK_Return
 
 #include "base/property_bag.h"
 #include "base/string_util.h"
@@ skipping 346 matching lines @@
 
     // TODO(shess): What if it didn't get first responder, and there is
     // no field editor?  This will do nothing.  Well, at least it won't
     // crash.  Think of something more productive to do, or prove that
     // it cannot occur and DCHECK appropriately.
     [[field_ currentEditor] setSelectedRange:range];
   }
 }
 
 void OmniboxViewMac::SetWindowTextAndCaretPos(const string16& text,
-                                              size_t caret_pos) {
+                                              size_t caret_pos,
+                                              bool update_popup,
+                                              bool notify_text_changed) {
   DCHECK_LE(caret_pos, text.size());
   SetTextAndSelectedRange(text, NSMakeRange(caret_pos, caret_pos));
 }
 
 void OmniboxViewMac::SetForcedQuery() {
   // We need to do this first, else |SetSelectedRange()| won't work.
   FocusLocation(true);
 
   const string16 current_text(GetText());
   const size_t start = current_text.find_first_not_of(kWhitespaceUTF16);
@@ skipping 221 matching lines @@
                range:ComponentToNSRange(scheme)];
   }
 }
 
 void OmniboxViewMac::OnTemporaryTextMaybeChanged(const string16& display_text,
                                                  bool save_original_selection) {
   if (save_original_selection)
     saved_temporary_selection_ = GetSelectedRange();
 
   suggest_text_length_ = 0;
-  SetWindowTextAndCaretPos(display_text, display_text.size());
+  SetWindowTextAndCaretPos(display_text, display_text.size(), false, false);
   model_->OnChanged();
   [field_ clearUndoChain];
 }
 
 void OmniboxViewMac::OnStartingIME() {
   // Reset the suggest text just before starting an IME composition session,
   // otherwise the IME composition may be interrupted when the suggest text
   // gets reset by the IME composition change.
   SetInstantSuggestion(string16(), false);
 }
@@ skipping 505 matching lines @@
 
 void OmniboxViewMac::PlaceCaretAt(NSUInteger pos) {
   DCHECK(pos <= GetTextLength());
   SetSelectedRange(NSMakeRange(pos, pos));
 }
 
 bool OmniboxViewMac::IsCaretAtEnd() const {
   const NSRange selection = GetSelectedRange();
   return selection.length == 0 && selection.location == GetTextLength();
 }