Hard coded UIRefreshPhase1 field trial for first run

Bug: 831971

Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: Id656f7fec7577080116e01c5883d9cbf21fd4ce8
Reviewed-on: https://chromium-review.googlesource.com/1128269
Commit-Queue: Peter Lee <[email protected]>
Reviewed-by: Alexei Svitkine <[email protected]>
Cr-Commit-Position: refs/heads/master@{#576960}

ios/chrome/browser/BUILD.gn

@@ -57,11 +57,14 @@ source_set("browser") {
     "install_time_util.mm",
     "installation_notifier.h",
     "installation_notifier.mm",
+    "ios_chrome_field_trials.cc",
     "ios_chrome_field_trials.h",
     "ios_chrome_flag_descriptions.cc",
     "ios_chrome_flag_descriptions.h",
     "ios_chrome_io_thread.h",
     "ios_chrome_io_thread.mm",
+    "ios_first_run_field_trials.cc",
+    "ios_first_run_field_trials.h",
     "notification_promo.cc",
     "notification_promo.h",
     "pref_names.cc",

ios/chrome/browser/ios_chrome_field_trials.cc

@@ -0,0 +1,105 @@
+// Copyright 2018 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 "ios/chrome/browser/ios_chrome_field_trials.h"
+
+#include <string>
+#include <vector>
+
+#include "base/metrics/field_trial.h"
+#include "components/variations/variations_associated_data.h"
+#include "components/version_info/version_info.h"
+#include "ios/chrome/browser/ios_first_run_field_trials.h"
+#include "ios/chrome/browser/ui/ui_feature_flags.h"
+#include "ios/chrome/common/channel_info.h"
+
+namespace {
+
+// Probabilities for all field trial groups add up to kTotalProbability.
+const base::FieldTrial::Probability kTotalProbability = 100;
+
+// Each field trial has 3 trial groups.
+// Default - Majority of users will be in default group which receive the
+//    default UI. In the case of UI Refresh rollout, this will be the new UI.
+// Old UI - A small percentage of users will be held back in the old UI for
+//    so usage metrics differences between users with old UI can be compared
+//    against users with new UI.
+// New UI - Same sized group as Old UI for comparison.
+const char kDefaultGroup[] = "NewUIRollout";
+const char kOldUIControlGroup[] = "OldUIControl";
+const char kNewUIExperimentGroup[] = "NewUIExperiment";
+// Experiment IDs defined for the above field trial groups.
+const variations::VariationID kDefaultTrialID = 3314527;
+const variations::VariationID kOldUIControlTrialID = 3314528;
+const variations::VariationID kNewUIExperimentTrialID = 3314529;
+
+// Returns the percentage of users who are to be held back in "old" UI. The
+// same percentage will be placed in a separate experiment group, but shown
+// the "new" UI such that there will be two equal sized groups for comparing
+// user behavior under "old" and "new" UI. Field trial configuration depends
+// on release channel.
+base::FieldTrial::Probability UIRefreshHoldbackPercent(
+    version_info::Channel channel) {
+  switch (channel) {
+    // Stable Channel has 3% of users held back with Old UI.
+    case version_info::Channel::STABLE:
+    case version_info::Channel::UNKNOWN:  // Same as DEFAULT
+      return 3;
+    // Beta Channel is 50/50 split between Old UI and New UI.
+    case version_info::Channel::BETA:
+      return 50;
+    // Canary and Dev is 100% rolled out with New UI.
+    case version_info::Channel::CANARY:
+    case version_info::Channel::DEV:
+      return 0;
+  }
+}
+
+// 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. This
+// sets up the field trial for UI Refresh.
+void SetupUIRefreshFieldTrial(base::FeatureList* feature_list) {
+  // Field trial configuration pre-defined here for UI Refresh should match the
+  // configuration stored on the servers. Server-stored configuration will
+  // override this pre-defined configuration.
+  base::FieldTrial::Probability holdback =
+      UIRefreshHoldbackPercent(GetChannel());
+  FirstRunFieldTrialConfig config("IOSUIRefreshRolloutWithHoldback");
+  config.AddGroup(kDefaultGroup, kDefaultTrialID,
+                  kTotalProbability - 2 * holdback);
+  config.AddGroup(kOldUIControlGroup, kOldUIControlTrialID, holdback);
+  config.AddGroup(kNewUIExperimentGroup, kNewUIExperimentTrialID, holdback);
+
+  scoped_refptr<base::FieldTrial> trial(
+      base::FieldTrialList::FactoryGetFieldTrial(
+          config.trial_name(), kTotalProbability, kDefaultGroup,
+          config.expire_year(), config.expire_month(),
+          config.expire_day_of_month(), 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());
+  }
+
+  // Tests which group this user has been assigned to. Based on the group,
+  // sets the UI Refresh Phase 1 feature flag.
+  const std::string& chosen_group_name = trial->GetGroupNameWithoutActivation();
+  base::FeatureList::OverrideState feature_state =
+      chosen_group_name == kOldUIControlGroup
+          ? base::FeatureList::OVERRIDE_DISABLE_FEATURE
+          : base::FeatureList::OVERRIDE_ENABLE_FEATURE;
+  feature_list->RegisterFieldTrialOverride(kUIRefreshPhase1.name, feature_state,
+                                           trial.get());
+}
+
+}  // namespace
+
+void IOSChromeFieldTrials::SetupFeatureControllingFieldTrials(
+    bool has_seed,
+    base::FeatureList* feature_list) {
+  SetupUIRefreshFieldTrial(feature_list);
+}

ios/chrome/browser/ios_chrome_field_trials.h

@@ -19,7 +19,7 @@ class IOSChromeFieldTrials : public variations::PlatformFieldTrials {
   void SetupFieldTrials() override {}
   void SetupFeatureControllingFieldTrials(
       bool has_seed,
-      base::FeatureList* feature_list) override {}
+      base::FeatureList* feature_list) override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(IOSChromeFieldTrials);

ios/chrome/browser/ios_first_run_field_trials.cc

@@ -0,0 +1,41 @@
+// Copyright 2018 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 "ios/chrome/browser/ios_first_run_field_trials.h"
+
+// FirstRunFieldTrialGroup
+FirstRunFieldTrialGroup::FirstRunFieldTrialGroup(
+    const std::string& name,
+    variations::VariationID variation,
+    base::FieldTrial::Probability percentage)
+    : name_(name), variation_(variation), percentage_(percentage) {}
+
+FirstRunFieldTrialGroup::~FirstRunFieldTrialGroup() {}
+
+// FirstRunFieldTrialConfig
+FirstRunFieldTrialConfig::FirstRunFieldTrialConfig(
+    const std::string& trial_name)
+    : FirstRunFieldTrialConfig(trial_name,
+                               base::FieldTrialList::kNoExpirationYear,
+                               1,
+                               1) {}
+
+FirstRunFieldTrialConfig::FirstRunFieldTrialConfig(
+    const std::string& trial_name,
+    int year,
+    int month,
+    int day_of_month)
+    : trial_name_(trial_name),
+      expire_year_(year),
+      expire_month_(month),
+      expire_day_of_month_(day_of_month) {}
+
+FirstRunFieldTrialConfig::~FirstRunFieldTrialConfig() {}
+
+void FirstRunFieldTrialConfig::AddGroup(
+    const std::string& name,
+    variations::VariationID variation,
+    base::FieldTrial::Probability percentage) {
+  groups_.emplace_back(name, variation, percentage);
+}

ios/chrome/browser/ios_first_run_field_trials.h

@@ -0,0 +1,75 @@
+// Copyright 2018 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 IOS_CHROME_BROWSER_IOS_FIRST_RUN_FIELD_TRIALS_H_
+#define IOS_CHROME_BROWSER_IOS_FIRST_RUN_FIELD_TRIALS_H_
+
+#include <string>
+#include <vector>
+
+#include "base/metrics/field_trial.h"
+#include "components/variations/variations_associated_data.h"
+
+// Helper class defining a FieldTrial group.
+class FirstRunFieldTrialGroup {
+ public:
+  FirstRunFieldTrialGroup(const std::string& name,
+                          variations::VariationID variation,
+                          base::FieldTrial::Probability percentage);
+  ~FirstRunFieldTrialGroup();
+
+  // 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_;
+};
+
+// Helper class defining a FieldTrial configuration that will be valid at the
+// time of Chrome First Run. Since server-provided FieldTrial configurations
+// that need to be downloaded will 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 FirstRunFieldTrialConfig {
+ public:
+  // Initializes with |trial_name| as the name of the FieldTrial with default
+  // duration.
+  FirstRunFieldTrialConfig(const std::string& trial_name);
+  // Initializes with |trial_name| as the name of the FieldTrial and one that
+  // ends on (year, month, day_of_month).
+  FirstRunFieldTrialConfig(const std::string& trial_name,
+                           int year,
+                           int month,
+                           int day_of_month);
+  ~FirstRunFieldTrialConfig();
+
+  // 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<FirstRunFieldTrialGroup>& groups() const { return groups_; }
+  // Accessors for this FieldTrial.
+  const std::string& trial_name() { return trial_name_; }
+  int expire_year() { return expire_year_; }
+  int expire_month() { return expire_month_; }
+  int expire_day_of_month() { return expire_day_of_month_; }
+
+ private:
+  std::string trial_name_;
+  std::vector<FirstRunFieldTrialGroup> groups_;
+  int expire_year_;
+  int expire_month_;
+  int expire_day_of_month_;
+
+  DISALLOW_COPY_AND_ASSIGN(FirstRunFieldTrialConfig);
+};
+
+#endif  // IOS_CHROME_BROWSER_IOS_FIRST_RUN_FIELD_TRIALS_H_