Enabled pressing TAB to cycle through the Omnibox results.

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

Index: chrome/browser/ui/cocoa/omnibox/omnibox_view_mac.mm
===================================================================
--- chrome/browser/ui/cocoa/omnibox/omnibox_view_mac.mm	(revision 117892)
+++ chrome/browser/ui/cocoa/omnibox/omnibox_view_mac.mm	(working copy)
@@ -364,7 +364,9 @@
 }
 
 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));
 }
@@ -606,7 +608,7 @@
     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];
 }