Remove hard coded HideShortcutsOnNtp field trial for new users.

Clean up the pref associated with this field trial, with deletion
slated after several milestones.
More details at http://doc/1rYBoi6Hm270SB1njw3BhM3Qo9puZn3iiINQy-gMaz4I

Bug: 988028
Change-Id: I5846351c4d66b0cf04b4f5c92b7de88db5d4e18d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1689496
Commit-Queue: Ramya Nagarajan <ramyan@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Cr-Commit-Position: refs/heads/master@{#681374}

chrome/browser/BUILD.gn

@@ -3304,10 +3304,6 @@ jumbo_split_static_library("browser") {
       "search/instant_service_factory.h",
       "search/instant_service_observer.cc",
       "search/instant_service_observer.h",
-      "search/local_ntp_first_run_field_trial_handler.cc",
-      "search/local_ntp_first_run_field_trial_handler.h",
-      "search/local_ntp_first_run_field_trials.cc",
-      "search/local_ntp_first_run_field_trials.h",
       "search/local_ntp_source.cc",
       "search/local_ntp_source.h",
       "search/most_visited_iframe_source.cc",

chrome/browser/chrome_browser_field_trials.cc

@@ -17,7 +17,6 @@
 #include "chrome/browser/metrics/chrome_metrics_service_accessor.h"
 #include "chrome/browser/metrics/chrome_metrics_service_client.h"
 #include "chrome/browser/metrics/chrome_metrics_services_manager_client.h"
-#include "chrome/browser/search/local_ntp_first_run_field_trial_handler.h"
 #include "chrome/common/channel_info.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/chrome_switches.h"
@@ -91,11 +90,6 @@ void ChromeBrowserFieldTrials::SetupFeatureControllingFieldTrials(
     chromeos::multidevice_setup::CreateFirstRunFieldTrial(feature_list);
 #endif
   }
-#if !defined(OS_ANDROID)
-  // TODO(crbug.com/944624) Remove hide shortcuts field trial
-  ntp_first_run::ActivateHideShortcutsOnNtpFieldTrial(feature_list,
-                                                      local_state_);
-#endif  // !defined(OS_ANDROID)
 }
 
 void ChromeBrowserFieldTrials::RegisterSyntheticTrials() {

chrome/browser/prefs/browser_prefs.cc

@@ -61,7 +61,6 @@
 #include "chrome/browser/push_messaging/push_messaging_app_identifier.h"
 #include "chrome/browser/renderer_host/pepper/device_id_fetcher.h"
 #include "chrome/browser/rlz/chrome_rlz_tracker_delegate.h"
-#include "chrome/browser/search/local_ntp_first_run_field_trial_handler.h"
 #include "chrome/browser/search/search.h"
 #include "chrome/browser/sharing/sharing_sync_preference.h"
 #include "chrome/browser/ssl/chrome_ssl_host_state_delegate.h"
@@ -463,6 +462,12 @@ const char kHasSeenWin10PromoPage[] = "browser.has_seen_win10_promo_page";
 // Deprecated 7/2019
 const char kSignedInTime[] = "signin.signedin_time";
 
+#if !defined(OS_ANDROID)
+// Deprecated 7/2019
+const char kNtpActivateHideShortcutsFieldTrial[] =
+    "ntp.activate_hide_shortcuts_field_trial";
+#endif  // !defined(OS_ANDROID)
+
 // Register prefs used only for migration (clearing or moving to a new key).
 void RegisterProfilePrefsForMigration(
     user_prefs::PrefRegistrySyncable* registry) {
@@ -585,7 +590,6 @@ void RegisterLocalState(PrefRegistrySimple* registry) {
   gcm::GCMChannelStatusSyncer::RegisterPrefs(registry);
   gcm::RegisterPrefs(registry);
   metrics::TabStatsTracker::RegisterPrefs(registry);
-  ntp_first_run::RegisterLocalStatePrefs(registry);
   RegisterBrowserPrefs(registry);
   StartupBrowserCreator::RegisterLocalStatePrefs(registry);
   task_manager::TaskManagerInterface::RegisterPrefs(registry);
@@ -677,6 +681,9 @@ void RegisterLocalState(PrefRegistrySimple* registry) {
 
   // Obsolete. See MigrateObsoleteBrowserPrefs().
   registry->RegisterIntegerPref(metrics::prefs::kStabilityExecutionPhase, 0);
+#if !defined(OS_ANDROID)
+  registry->RegisterBooleanPref(kNtpActivateHideShortcutsFieldTrial, false);
+#endif  // !defined(OS_ANDROID)
 
 #if defined(TOOLKIT_VIEWS)
   RegisterBrowserViewLocalPrefs(registry);
@@ -992,6 +999,11 @@ void MigrateObsoleteBrowserPrefs(Profile* profile, PrefService* local_state) {
   // Added 6/2019.
   local_state->ClearPref(kHasSeenWin10PromoPage);
 #endif  // defined(OS_WIN)
+
+#if !defined(OS_ANDROID)
+  // Added 7/2019.
+  local_state->ClearPref(kNtpActivateHideShortcutsFieldTrial);
+#endif  // !defined(OS_ANDROID)
 }
 
 // This method should be periodically pruned of year+ old migrations.

chrome/browser/search/local_ntp_first_run_field_trial_handler.cc

-// Copyright 2019 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/local_ntp_first_run_field_trial_handler.h"
-
-#include "base/feature_list.h"
-#include "chrome/browser/first_run/first_run.h"
-#include "chrome/browser/metrics/chrome_metrics_service_accessor.h"
-#include "chrome/browser/search/local_ntp_first_run_field_trials.h"
-#include "chrome/browser/search/ntp_features.h"
-#include "chrome/common/channel_info.h"
-#include "chrome/common/pref_names.h"
-#include "components/prefs/pref_registry_simple.h"
-#include "components/prefs/pref_service.h"
-#include "components/version_info/version_info.h"
-
-namespace {
-
-// Probabilities for all field trial groups add up to kTotalProbability.
-const base::FieldTrial::Probability kTotalProbability = 100;
-
-const char kTrialName[] = "HideShortcutsOnNtp";
-// Each field trial has 3 groups.
-// HideShortcutsExperiment - see the NTP with shortcuts hidden.
-// HideShortcutsControl - see shortcuts on the NTP; same size as the
-//   HideShortcutsExperiment group.
-// Default - see shortcuts on the NTP; are not part of the experiment.
-const char kExperimentGroup[] = "HideShortcutsExperiment";
-const char kControlGroup[] = "HideShortcutsControl";
-const char kDefaultGroup[] = "Default";
-
-void LoadConfigByChannel(const version_info::Channel& channel,
-                         variations::VariationID* experiment_id,
-                         variations::VariationID* control_id,
-                         base::FieldTrial::Probability* experiment_size) {
-  switch (channel) {
-    // Shortcuts are hidden for 100% of new users on the Canary / Dev Channels.
-    case version_info::Channel::CANARY:
-    case version_info::Channel::DEV:
-    case version_info::Channel::UNKNOWN:
-      *experiment_id = 3315271;
-      *control_id = 3315272;
-      *experiment_size = 50;
-      break;
-    // Shortcuts are hidden for 50% of new users on the Beta Channel.
-    case version_info::Channel::BETA:
-      *experiment_id = 3315273;
-      *control_id = 3315274;
-      *experiment_size = 50;
-      break;
-    // Shortcuts are hidden for 1% of new users on the Stable Channel.
-    case version_info::Channel::STABLE:
-      *experiment_id = 3315275;
-      *control_id = 3315276;
-      *experiment_size = 1;
-      break;
-  }
-}
-
-}  // namespace
-
-namespace ntp_first_run {
-
-void RegisterLocalStatePrefs(PrefRegistrySimple* registry) {
-  registry->RegisterBooleanPref(prefs::kNtpActivateHideShortcutsFieldTrial,
-                                false);
-}
-
-void ActivateHideShortcutsOnNtpFieldTrial(base::FeatureList* feature_list,
-                                          PrefService* local_state) {
-  // The field trial is activated for fresh installs, or for clients that were
-  // previously activated (during a fresh install). For all other existing
-  // clients, the trial is not activated, and the experiment is unavailable.
-  if (!first_run::IsChromeFirstRun() &&
-      !local_state->GetBoolean(prefs::kNtpActivateHideShortcutsFieldTrial)) {
-    return;
-  }
-  // Field trials do not take effect until configurations have been downloaded.
-  // In order for field trials involving substantial UI changes to take effect
-  // at first run, the configuration must be pre-defined in client code.
-  variations::VariationID experiment_id;
-  variations::VariationID control_id;
-  base::FieldTrial::Probability experiment_size;
-  LoadConfigByChannel(chrome::GetChannel(), &experiment_id, &control_id,
-                      &experiment_size);
-
-  LocalNtpFirstRunFieldTrialConfig config(kTrialName);
-  config.AddGroup(kExperimentGroup, experiment_id, experiment_size);
-  config.AddGroup(kControlGroup, control_id, experiment_size);
-
-  // The field trial can only be loaded once per browser session
-  scoped_refptr<base::FieldTrial> trial(
-      base::FieldTrialList::FactoryGetFieldTrial(
-          config.trial_name(), kTotalProbability, kDefaultGroup,
-          base::FieldTrial::ONE_TIME_RANDOMIZED,
-          /*default_group_number=*/nullptr));
-  for (const auto& group : config.groups()) {
-    variations::AssociateGoogleVariationID(variations::GOOGLE_WEB_PROPERTIES,
-                                           config.trial_name(), group.name(),
-                                           group.variation());
-    trial->AppendGroup(group.name(), group.percentage());
-  }
-
-  const std::string& chosen_group_name = trial->GetGroupNameWithoutActivation();
-  base::FeatureList::OverrideState feature_state =
-      (chosen_group_name == kExperimentGroup)
-          ? base::FeatureList::OVERRIDE_ENABLE_FEATURE
-          : base::FeatureList::OVERRIDE_DISABLE_FEATURE;
-
-  feature_list->RegisterFieldTrialOverride(features::kHideShortcutsOnNtp.name,
-                                           feature_state, trial.get());
-
-  // This pref ensures the field trial can be loaded again for clients that
-  // were activated in a previous browser session.
-  local_state->SetBoolean(prefs::kNtpActivateHideShortcutsFieldTrial, true);
-}
-
-}  // namespace ntp_first_run

chrome/browser/search/local_ntp_first_run_field_trial_handler.h

-// Copyright 2019 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_SEARCH_LOCAL_NTP_FIRST_RUN_FIELD_TRIAL_HANDLER_H_
-#define CHROME_BROWSER_SEARCH_LOCAL_NTP_FIRST_RUN_FIELD_TRIAL_HANDLER_H_
-
-class PrefRegistrySimple;
-class PrefService;
-
-namespace base {
-class FeatureList;
-}
-
-namespace ntp_first_run {
-
-// Registers hide shortcuts field trial activation in Local State.
-void RegisterLocalStatePrefs(PrefRegistrySimple* registry);
-
-// Loads the HideShortcutsOnNtp field trial config, and establishes the chosen
-// group for this client as being part of the experiment, control or default.
-void ActivateHideShortcutsOnNtpFieldTrial(base::FeatureList* feature_list,
-                                          PrefService* local_state);
-
-}  // namespace ntp_first_run
-
-#endif  // CHROME_BROWSER_SEARCH_LOCAL_NTP_FIRST_RUN_FIELD_TRIAL_HANDLER_H_

chrome/browser/search/local_ntp_first_run_field_trials.cc

-// Copyright 2019 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/local_ntp_first_run_field_trials.h"
-
-LocalNtpFirstRunFieldTrialGroup::LocalNtpFirstRunFieldTrialGroup(
-    const std::string& name,
-    variations::VariationID variation,
-    base::FieldTrial::Probability percentage)
-    : name_(name), variation_(variation), percentage_(percentage) {}
-
-LocalNtpFirstRunFieldTrialGroup::~LocalNtpFirstRunFieldTrialGroup() = default;
-
-LocalNtpFirstRunFieldTrialConfig::LocalNtpFirstRunFieldTrialConfig(
-    const std::string& trial_name)
-    : trial_name_(trial_name) {}
-
-LocalNtpFirstRunFieldTrialConfig::~LocalNtpFirstRunFieldTrialConfig() = default;
-
-void LocalNtpFirstRunFieldTrialConfig::AddGroup(
-    const std::string& name,
-    variations::VariationID variation,
-    base::FieldTrial::Probability percentage) {
-  groups_.emplace_back(name, variation, percentage);
-}

chrome/browser/search/local_ntp_first_run_field_trials.h

-// Copyright 2019 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_SEARCH_LOCAL_NTP_FIRST_RUN_FIELD_TRIALS_H_
-#define CHROME_BROWSER_SEARCH_LOCAL_NTP_FIRST_RUN_FIELD_TRIALS_H_
-
-#include "base/macros.h"
-#include "components/variations/variations_associated_data.h"
-
-// Defines a FieldTrial group.
-class LocalNtpFirstRunFieldTrialGroup {
- public:
-  LocalNtpFirstRunFieldTrialGroup(const std::string& name,
-                                  variations::VariationID variation,
-                                  base::FieldTrial::Probability percentage);
-  ~LocalNtpFirstRunFieldTrialGroup();
-
-  // Accessors for this FieldTrial group.
-  const std::string& name() const { return name_; }
-  variations::VariationID variation() const { return variation_; }
-  base::FieldTrial::Probability percentage() const { return percentage_; }
-
- private:
-  std::string name_;
-  variations::VariationID variation_;
-  base::FieldTrial::Probability percentage_;
-};
-
-// Defines a FieldTrial configuration that will be valid at the time of Chrome
-// First Run. Since server-provided FieldTrial configurations need to be
-// downloaded, they do not take effect until at least the second run.
-// FieldTrials involving substantial UI changes that need to take effect at
-// first run must be pre-defined in client code.
-class LocalNtpFirstRunFieldTrialConfig {
- public:
-  // Initializes with |trial_name| as the name of the FieldTrial with default
-  // duration.
-  explicit LocalNtpFirstRunFieldTrialConfig(const std::string& trial_name);
-  ~LocalNtpFirstRunFieldTrialConfig();
-
-  // Adds a new FieldTrial group of |name| with a probability of |percentage|.
-  // |variation| defines a server-side variation configuration.
-  void AddGroup(const std::string& name,
-                variations::VariationID variation,
-                base::FieldTrial::Probability percentage);
-
-  // Returns a vector of FieldTrial groups for this FieldTrial configuration.
-  const std::vector<LocalNtpFirstRunFieldTrialGroup>& groups() const {
-    return groups_;
-  }
-  // Accessors for this FieldTrial.
-  const std::string& trial_name() { return trial_name_; }
-
- private:
-  std::string trial_name_;
-  std::vector<LocalNtpFirstRunFieldTrialGroup> groups_;
-
-  DISALLOW_COPY_AND_ASSIGN(LocalNtpFirstRunFieldTrialConfig);
-};
-
-#endif  // CHROME_BROWSER_SEARCH_LOCAL_NTP_FIRST_RUN_FIELD_TRIALS_H_

chrome/common/pref_names.cc

@@ -1626,11 +1626,6 @@ const char kNtpCollapsedSnapshotDocument[] = "ntp.collapsed_snapshot_document";
 // Keeps track of sync promo collapsed state in the Other Devices menu.
 const char kNtpCollapsedSyncPromo[] = "ntp.collapsed_sync_promo";
 #else
-// Tracks whether a field trial to hide shortcuts on the NTP has been activated.
-// It is only activated for fresh installs, and remains active for those clients
-// after a browser restart.
-const char kNtpActivateHideShortcutsFieldTrial[] =
-    "ntp.activate_hide_shortcuts_field_trial";
 // Holds info for New Tab Page custom background
 const char kNtpCustomBackgroundDict[] = "ntp.custom_background_dict";
 const char kNtpCustomBackgroundLocalToDevice[] =

chrome/common/pref_names.h

@@ -550,7 +550,6 @@ extern const char kNtpCollapsedRecentlyClosedTabs[];
 extern const char kNtpCollapsedSnapshotDocument[];
 extern const char kNtpCollapsedSyncPromo[];
 #else
-extern const char kNtpActivateHideShortcutsFieldTrial[];
 extern const char kNtpCustomBackgroundDict[];
 extern const char kNtpCustomBackgroundLocalToDevice[];
 extern const char kNtpSearchSuggestionsBlocklist[];