Remove a variety of no-longer-used query params.

chrome/browser/search/instant_service_observer.cc

 // Copyright 2013 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/search/instant_service_observer.h"
 
 void InstantServiceObserver::ThemeInfoChanged(const ThemeBackgroundInfo&) {
 }
 
 void InstantServiceObserver::MostVisitedItemsChanged(
     const std::vector<InstantMostVisitedItem>&) {
 }
 
 void InstantServiceObserver::DefaultSearchProviderChanged(
     bool google_base_url_domain_changed) {
 }
-
-void InstantServiceObserver::OmniboxStartMarginChanged(
-    int omnibox_start_margin) {
-}