Introduce a field trial for Instant.

chrome/browser/instant/instant_controller.cc

 // 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.
 
 #include "chrome/browser/instant/instant_controller.h"
 
 #include "base/command_line.h"
 #include "base/message_loop.h"
 #include "base/metrics/histogram.h"
 #include "build/build_config.h"
 #include "chrome/browser/autocomplete/autocomplete_match.h"
 #include "chrome/browser/instant/instant_delegate.h"
+#include "chrome/browser/instant/instant_field_trial.h"
 #include "chrome/browser/instant/instant_loader.h"
 #include "chrome/browser/instant/instant_loader_manager.h"
 #include "chrome/browser/instant/promo_counter.h"
 #include "chrome/browser/platform_util.h"
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/browser/prerender/prerender_manager.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/search_engines/template_url.h"
 #include "chrome/browser/search_engines/template_url_service.h"
 #include "chrome/browser/search_engines/template_url_service_factory.h"
@@ skipping 19 matching lines @@
 InstantController::InstantController(Profile* profile,
                                      InstantDelegate* delegate)
     : delegate_(delegate),
       tab_contents_(NULL),
       is_active_(false),
       displayable_loader_(NULL),
       commit_on_mouse_up_(false),
       last_transition_type_(PageTransition::LINK),
       ALLOW_THIS_IN_INITIALIZER_LIST(destroy_factory_(this)) {
   PrefService* service = profile->GetPrefs();
-  if (service) {
-    // kInstantWasEnabledOnce was added after instant, set it now to make sure
-    // it is correctly set.
+  if (service && !instant_field_trial::IsExperiment(profile)) {
+    // kInstantEnabledOnce was added after instant, set it now to make sure it
+    // is correctly set.
     service->SetBoolean(prefs::kInstantEnabledOnce, true);
   }
 }
 
 InstantController::~InstantController() {
 }
 
 // static
 void InstantController::RegisterUserPrefs(PrefService* prefs) {
   prefs->RegisterBooleanPref(prefs::kInstantConfirmDialogShown,
@@ skipping 28 matching lines @@
       // Histogram from 1 hour to 30 days.
       UMA_HISTOGRAM_CUSTOM_COUNTS("Instant.EnabledTime.Predictive",
                                   delta.InHours(), 1, 30 * 24, 50);
     }
   }
 }
 
 // static
 bool InstantController::IsEnabled(Profile* profile) {
   PrefService* prefs = profile->GetPrefs();
-  return prefs->GetBoolean(prefs::kInstantEnabled);
+  return prefs->GetBoolean(prefs::kInstantEnabled) ||
+         instant_field_trial::IsExperiment(profile);
 }
 
 // static
 void InstantController::Enable(Profile* profile) {
   PromoCounter* promo_counter = profile->GetInstantPromoCounter();
   if (promo_counter)
     promo_counter->Hide();
 
   PrefService* service = profile->GetPrefs();
   if (!service)
@@ skipping 583 matching lines @@
 
   // Extension keywords don't have a real destination URL.
   if (match.template_url && match.template_url->IsExtensionKeyword())
     return PREVIEW_CONDITION_EXTENSION_KEYWORD;
 
   // Was the host blacklisted?
   if (host_blacklist_ && host_blacklist_->count(match.destination_url.host()))
     return PREVIEW_CONDITION_BLACKLISTED;
 
   const CommandLine* cl = CommandLine::ForCurrentProcess();
-  if (cl->HasSwitch(switches::kRestrictInstantToSearch) &&
+  if ((cl->HasSwitch(switches::kRestrictInstantToSearch) ||
+       instant_field_trial::IsExperiment(tab_contents_->profile())) &&
       match.type != AutocompleteMatch::SEARCH_WHAT_YOU_TYPED &&
       match.type != AutocompleteMatch::SEARCH_HISTORY &&
       match.type != AutocompleteMatch::SEARCH_SUGGEST &&
       match.type != AutocompleteMatch::SEARCH_OTHER_ENGINE) {
     return PREVIEW_CONDITION_INSTANT_SEARCH_ONLY;
   }
 
   return PREVIEW_CONDITION_SUCCESS;
 }
 
@@ skipping 14 matching lines @@
   if (destroy_factory_.empty()) {
     MessageLoop::current()->PostTask(
         FROM_HERE, destroy_factory_.NewRunnableMethod(
             &InstantController::DestroyLoaders));
   }
 }
 
 void InstantController::DestroyLoaders() {
   loaders_to_destroy_.reset();
 }