Moves instant back into flags.

chrome/renderer/search_extension.cc

 // Copyright (c) 2010 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/renderer/search_extension.h"
 
 #include "base/command_line.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/render_messages_params.h"
 #include "chrome/renderer/render_view.h"
@@ skipping 68 matching lines @@
   if (!suggest.length()) return v8::Undefined();
 
   RenderView* render_view = GetRenderView();
   if (!render_view) return v8::Undefined();
 
   render_view->SetSuggestResult(suggest);
   return v8::Undefined();
 }
 
 v8::Extension* SearchExtension::Get() {
-  return new SearchExtensionWrapper();
+  if (CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableMatchPreview)) {
+    return new SearchExtensionWrapper();
+  }
+  return NULL;
 }
 
 }  // namespace extensions_v8