Introduce a field trial for Instant.

chrome/browser/autocomplete/autocomplete.h

 // 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.
 
 #ifndef CHROME_BROWSER_AUTOCOMPLETE_AUTOCOMPLETE_H_
 #define CHROME_BROWSER_AUTOCOMPLETE_AUTOCOMPLETE_H_
 #pragma once
 
 #include <map>
 #include <string>
@@ skipping 581 matching lines @@
   // Used to indicate an index that is not selected in a call to Update().
   static const int kNoItemSelected;
 
   // Normally, you will call the first constructor.  Unit tests can use the
   // second to set the providers to some known testing providers.  The default
   // providers will be overridden and the controller will take ownership of the
   // providers, Release()ing them on destruction.
   AutocompleteController(Profile* profile,
                          AutocompleteControllerDelegate* delegate);
 #ifdef UNIT_TEST
-  explicit AutocompleteController(const ACProviders& providers)
+  AutocompleteController(const ACProviders& providers, Profile* profile)
       : delegate_(NULL),
         providers_(providers),
         keyword_provider_(NULL),
         search_provider_(NULL),
         done_(true),
-        in_start_(false) {
+        in_start_(false),
+        profile_(profile) {
   }
 #endif
   ~AutocompleteController();
 
   // Invoked when the profile changes. This forwards the call down to all
   // the AutocompleteProviders.
   void SetProfile(Profile* profile);
 
   // Starts an autocomplete query, which continues until all providers are
   // done or the query is Stop()ed.  It is safe to Start() a new query without
@@ skipping 102 matching lines @@
   // invokes |ExpireCopiedEntries|.
   base::OneShotTimer<AutocompleteController> expire_timer_;
 
   // True if a query is not currently running.
   bool done_;
 
   // Are we in Start()? This is used to avoid updating |result_| and sending
   // notifications until Start() has been invoked on all providers.
   bool in_start_;
 
+  Profile* profile_;
+
   DISALLOW_COPY_AND_ASSIGN(AutocompleteController);
 };
 
 // AutocompleteLog ------------------------------------------------------------
 
 // The data to log (via the metrics service) when the user selects an item
 // from the omnibox popup.
 struct AutocompleteLog {
   AutocompleteLog(const string16& text,
                   AutocompleteInput::Type input_type,
@@ skipping 12 matching lines @@
   AutocompleteInput::Type input_type;
   // Selected index (if selected) or -1 (AutocompletePopupModel::kNoMatch).
   size_t selected_index;
   // Inline autocompleted length (if displayed).
   size_t inline_autocompleted_length;
   // Result set.
   const AutocompleteResult& result;
 };
 
 #endif  // CHROME_BROWSER_AUTOCOMPLETE_AUTOCOMPLETE_H_