Don't call AcceptCurrentInstantPreview() when the user hits Tab.

chrome/browser/ui/omnibox/omnibox_edit_model.h

 // Copyright 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.
 
 #ifndef CHROME_BROWSER_UI_OMNIBOX_OMNIBOX_EDIT_MODEL_H_
 #define CHROME_BROWSER_UI_OMNIBOX_OMNIBOX_EDIT_MODEL_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 158 matching lines @@
   // Sets the suggestion text.
   void SetInstantSuggestion(const InstantSuggestion& suggestion);
 
   // Commits the suggested text. If |skip_inline_autocomplete| is true then the
   // suggested text will be committed as final text as if it's inputted by the
   // user, rather than as inline autocomplete suggest.
   // Returns true if the text was committed.
   // TODO: can the return type be void?
   bool CommitSuggestedText(bool skip_inline_autocomplete);
 
-  // Accepts the currently showing Instant preview, if any, and returns true.
-  // Returns false if there is no Instant preview showing.
-  bool AcceptCurrentInstantPreview();
-
   // Invoked any time the text may have changed in the edit. Updates Instant and
   // notifies the controller.
   void OnChanged();
 
   // Reverts the edit model back to its unedited state (permanent text showing,
   // no user input in progress).
   void Revert();
 
   // Directs the popup to start autocomplete.
   void StartAutocomplete(bool has_selected_text,
@@ skipping 366 matching lines @@
   // an exact keyword match.  If this is true then keyword mode will be
   // triggered automatically if the input is "<keyword> <search string>".  We
   // allow this when CreatedKeywordSearchByInsertingSpaceInMiddle() is true.
   // This has no effect if we're already in keyword mode.
   bool allow_exact_keyword_match_;
 
   DISALLOW_COPY_AND_ASSIGN(OmniboxEditModel);
 };
 
 #endif  // CHROME_BROWSER_UI_OMNIBOX_OMNIBOX_EDIT_MODEL_H_