Add "day zero" experiment feature & metrics

android/java/org/chromium/base/BraveFeatureList.java

@@ -31,6 +31,6 @@ public abstract class BraveFeatureList {
     public static final String AI_CHAT = "AIChat";
     public static final String BRAVE_SHOW_STRICT_FINGERPRINTING_MODE =
             "BraveShowStrictFingerprintingMode";
-    public static final String BRAVE_ZERO_DAY_FLAG_ANDROID = "BraveZeroDayFlagAndroid";
+    public static final String BRAVE_DAY_ZERO_EXPERIMENT = "BraveDayZeroExperiment";
     public static final String BRAVE_FALLBACK_DOH_PROVIDER = "BraveFallbackDoHProvider";
 }

browser/about_flags.cc

@@ -372,18 +372,9 @@
       kOsAndroid,                                                             \
       FEATURE_VALUE_TYPE(safe_browsing::features::kBraveAndroidSafeBrowsing), \
   })
-#define BRAVE_ZERO_DAY_FLAG_ANDROID                                        \
-  EXPAND_FEATURE_ENTRIES({                                                 \
-      "brave-zero-day-flag-android",                                       \
-      "ZeroDayFlag flag for product test",                                 \
-      "This flag will be set through griffin to perform product testing",  \
-      kOsAndroid,                                                          \
-      FEATURE_VALUE_TYPE(preferences::features::kBraveZeroDayFlagAndroid), \
-  })
 #else
 #define BRAVE_BACKGROUND_VIDEO_PLAYBACK_ANDROID
 #define BRAVE_SAFE_BROWSING_ANDROID
-#define BRAVE_ZERO_DAY_FLAG_ANDROID
 #endif  // BUILDFLAG(IS_ANDROID)
 
 #if !BUILDFLAG(IS_ANDROID)
@@ -992,7 +983,6 @@
   BRAVE_COMMANDS_FEATURE_ENTRIES                                               \
   BRAVE_BACKGROUND_VIDEO_PLAYBACK_ANDROID                                      \
   BRAVE_SAFE_BROWSING_ANDROID                                                  \
-  BRAVE_ZERO_DAY_FLAG_ANDROID                                                  \
   BRAVE_CHANGE_ACTIVE_TAB_ON_SCROLL_EVENT_FEATURE_ENTRIES                      \
   BRAVE_TABS_FEATURE_ENTRIES                                                   \
   BRAVE_AI_CHAT                                                                \

browser/android/preferences/features.cc

@@ -15,9 +15,5 @@ BASE_FEATURE(kBraveBackgroundVideoPlayback,
              "BraveBackgroundVideoPlayback",
              base::FEATURE_DISABLED_BY_DEFAULT);
 
-BASE_FEATURE(kBraveZeroDayFlagAndroid,
-             "BraveZeroDayFlagAndroid",
-             base::FEATURE_DISABLED_BY_DEFAULT);
-
 }  // namespace features
 }  // namespace preferences

browser/android/preferences/features.h

@@ -12,7 +12,6 @@ namespace preferences {
 namespace features {
 
 BASE_DECLARE_FEATURE(kBraveBackgroundVideoPlayback);
-BASE_DECLARE_FEATURE(kBraveZeroDayFlagAndroid);
 
 }  // namespace features
 }  // namespace preferences

browser/brave_browser_features.cc

@@ -35,4 +35,10 @@ BASE_FEATURE(kBraveWebViewRoundedCorners,
              "brave-web-view-rounded-corners",
              base::FEATURE_DISABLED_BY_DEFAULT);
 
+// Enable "day zero" experiment modifications, for potential user
+// retention improvements.
+BASE_FEATURE(kBraveDayZeroExperiment,
+             "BraveDayZeroExperiment",
+             base::FEATURE_DISABLED_BY_DEFAULT);
+
 }  // namespace features

browser/brave_browser_features.h

@@ -14,7 +14,7 @@ BASE_DECLARE_FEATURE(kBraveCleanupSessionCookiesOnSessionRestore);
 BASE_DECLARE_FEATURE(kBraveCopyCleanLinkByDefault);
 BASE_DECLARE_FEATURE(kBraveOverrideDownloadDangerLevel);
 BASE_DECLARE_FEATURE(kBraveWebViewRoundedCorners);
-BASE_DECLARE_FEATURE(kBraveZeroDayFlagAndroid);
+BASE_DECLARE_FEATURE(kBraveDayZeroExperiment);
 
 }  // namespace features
 

browser/brave_stats/brave_stats_updater.cc

@@ -12,8 +12,10 @@
 #include "base/command_line.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/system/sys_info.h"
+#include "brave/browser/brave_browser_features.h"
 #include "brave/browser/brave_stats/brave_stats_updater_params.h"
 #include "brave/browser/brave_stats/buildflags.h"
+#include "brave/browser/brave_stats/first_run_util.h"
 #include "brave/browser/brave_stats/switches.h"
 #include "brave/common/brave_channel_info.h"
 #include "brave/components/brave_ads/core/public/prefs/pref_names.h"
@@ -26,6 +28,7 @@
 #include "brave/components/rpill/common/rpill.h"
 #include "brave/components/version_info/version_info.h"
 #include "chrome/browser/browser_process.h"
+#include "chrome/browser/first_run/first_run.h"
 #include "chrome/browser/net/system_network_context_manager.h"
 #include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/common/channel_info.h"
@@ -107,7 +110,10 @@ BraveStatsUpdater::BraveStatsUpdater(PrefService* pref_service,
   }
 
   general_browser_usage_p3a_ =
-      std::make_unique<misc_metrics::GeneralBrowserUsage>(pref_service);
+      std::make_unique<misc_metrics::GeneralBrowserUsage>(
+          pref_service,
+          base::FeatureList::IsEnabled(features::kBraveDayZeroExperiment),
+          first_run::IsChromeFirstRun(), GetFirstRunTime(pref_service));
 
   if (profile_manager != nullptr) {
     g_browser_process->profile_manager()->AddObserver(this);

chromium_src/chrome/browser/flags/android/chrome_feature_list.cc

@@ -37,7 +37,6 @@
     &brave_wallet::features::kNativeBraveWalletFeature,                 \
     &playlist::features::kPlaylist,                                     \
     &preferences::features::kBraveBackgroundVideoPlayback,              \
-    &preferences::features::kBraveZeroDayFlagAndroid,                   \
     &request_otr::features::kBraveRequestOTRTab,                        \
     &safe_browsing::features::kBraveAndroidSafeBrowsing,                \
     &speedreader::kSpeedreaderFeature,                                  \

components/misc_metrics/general_browser_usage.cc

@@ -6,6 +6,7 @@
 #include "brave/components/misc_metrics/general_browser_usage.h"
 
 #include "base/metrics/histogram_macros.h"
+#include "base/time/time.h"
 #include "brave/components/misc_metrics/pref_names.h"
 #include "brave/components/p3a_utils/bucket.h"
 #include "brave/components/time_period_storage/iso_weekly_storage.h"
@@ -24,16 +25,31 @@ constexpr int kProfileCountBuckets[] = {0, 1, 2, 3, 5};
 
 }  // namespace
 
-GeneralBrowserUsage::GeneralBrowserUsage(PrefService* local_state) {
+GeneralBrowserUsage::GeneralBrowserUsage(PrefService* local_state,
+                                         bool day_zero_experiment_enabled,
+                                         bool is_first_run,
+                                         base::Time first_run_time)
+    : local_state_(local_state), first_run_time_(first_run_time) {
   usage_storage_ = std::make_unique<ISOWeeklyStorage>(
       local_state, kMiscMetricsBrowserUsageList);
+
+  if (is_first_run) {
+    if (day_zero_experiment_enabled) {
+      local_state->SetBoolean(kMiscMetricsDayZeroAtInstall, true);
+    }
+    if (first_run_time.is_null()) {
+      first_run_time_ = base::Time::Now();
+    }
+  }
+
   Update();
 }
 
 GeneralBrowserUsage::~GeneralBrowserUsage() = default;
 
 void GeneralBrowserUsage::RegisterPrefs(PrefRegistrySimple* registry) {
   registry->RegisterListPref(kMiscMetricsBrowserUsageList);
+  registry->RegisterBooleanPref(kMiscMetricsDayZeroAtInstall, false);
 }
 
 void GeneralBrowserUsage::ReportWeeklyUse() {
@@ -42,6 +58,20 @@ void GeneralBrowserUsage::ReportWeeklyUse() {
                              usage_storage_->GetLastISOWeekSum(), 8);
 }
 
+#if BUILDFLAG(IS_ANDROID) || BUILDFLAG(IS_WIN)
+void GeneralBrowserUsage::ReportInstallTime() {
+  int days_since_install = (base::Time::Now() - first_run_time_).InDays();
+  if (days_since_install < 0 || days_since_install > 30) {
+    return;
+  }
+  const char* histogram_name =
+      local_state_->GetBoolean(kMiscMetricsDayZeroAtInstall)
+          ? kDayZeroOnInstallTime
+          : kDayZeroOffInstallTime;
+  base::UmaHistogramExactLinear(histogram_name, days_since_install, 31);
+}
+#endif  // BUILDFLAG(IS_ANDROID) || BUILDFLAG(IS_WIN)
+
 void GeneralBrowserUsage::ReportProfileCount(size_t count) {
 #if !BUILDFLAG(IS_ANDROID)
   p3a_utils::RecordToHistogramBucket(kProfileCountHistogramName,
@@ -56,6 +86,9 @@ void GeneralBrowserUsage::SetUpUpdateTimer() {
 
 void GeneralBrowserUsage::Update() {
   ReportWeeklyUse();
+#if BUILDFLAG(IS_ANDROID) || BUILDFLAG(IS_WIN)
+  ReportInstallTime();
+#endif  // BUILDFLAG(IS_ANDROID) || BUILDFLAG(IS_WIN)
 
   SetUpUpdateTimer();
 }

components/misc_metrics/general_browser_usage.h

@@ -8,6 +8,7 @@
 
 #include <memory>
 
+#include "base/memory/raw_ptr.h"
 #include "base/timer/wall_clock_timer.h"
 
 class PrefRegistrySimple;
@@ -19,9 +20,18 @@ namespace misc_metrics {
 inline constexpr char kWeeklyUseHistogramName[] = "Brave.Core.WeeklyUsage";
 inline constexpr char kProfileCountHistogramName[] = "Brave.Core.ProfileCount";
 
+#if BUILDFLAG(IS_ANDROID) || BUILDFLAG(IS_WIN)
+inline constexpr char kDayZeroOnInstallTime[] = "Brave.DayZero.On.InstallTime";
+inline constexpr char kDayZeroOffInstallTime[] =
+    "Brave.DayZero.Off.InstallTime";
+#endif  // BUILDFLAG(IS_ANDROID) || BUILDFLAG(IS_WIN)
+
 class GeneralBrowserUsage {
  public:
-  explicit GeneralBrowserUsage(PrefService* local_state);
+  GeneralBrowserUsage(PrefService* local_state,
+                      bool day_zero_experiment_enabled,
+                      bool is_first_run,
+                      base::Time first_run_time);
   ~GeneralBrowserUsage();
 
   GeneralBrowserUsage(const GeneralBrowserUsage&) = delete;
@@ -33,11 +43,16 @@ class GeneralBrowserUsage {
 
  private:
   void ReportWeeklyUse();
+#if BUILDFLAG(IS_ANDROID) || BUILDFLAG(IS_WIN)
+  void ReportInstallTime();
+#endif  // BUILDFLAG(IS_ANDROID) || BUILDFLAG(IS_WIN)
 
   void SetUpUpdateTimer();
 
   void Update();
 
+  raw_ptr<PrefService> local_state_;
+  base::Time first_run_time_;
   std::unique_ptr<ISOWeeklyStorage> usage_storage_;
 
   base::WallClockTimer report_timer_;

components/misc_metrics/general_browser_usage_unittest.cc

@@ -33,19 +33,26 @@ class GeneralBrowserUsageUnitTest : public testing::Test {
       days_until_monday = 1;
     }
     task_environment_.AdvanceClock(base::Days(days_until_monday));
-
-    general_browser_usage_ =
-        std::make_unique<GeneralBrowserUsage>(&local_state_);
   }
 
  protected:
+  void SetUpUsage(bool day_zero_experiment_enabled,
+                  bool is_first_run,
+                  base::Time first_run_time) {
+    general_browser_usage_ = std::make_unique<GeneralBrowserUsage>(
+        &local_state_, day_zero_experiment_enabled, is_first_run,
+        first_run_time);
+  }
+
   content::BrowserTaskEnvironment task_environment_;
   TestingPrefServiceSimple local_state_;
   base::HistogramTester histogram_tester_;
   std::unique_ptr<GeneralBrowserUsage> general_browser_usage_;
 };
 
 TEST_F(GeneralBrowserUsageUnitTest, WeeklyUsage) {
+  SetUpUsage(false, true, base::Time::Now());
+
   histogram_tester_.ExpectUniqueSample(kWeeklyUseHistogramName, 0, 1);
 
   task_environment_.FastForwardBy(base::Days(1));
@@ -61,6 +68,8 @@ TEST_F(GeneralBrowserUsageUnitTest, WeeklyUsage) {
 
 #if !BUILDFLAG(IS_ANDROID)
 TEST_F(GeneralBrowserUsageUnitTest, ProfileCount) {
+  SetUpUsage(false, true, base::Time::Now());
+
   histogram_tester_.ExpectTotalCount(kProfileCountHistogramName, 0);
 
   general_browser_usage_->ReportProfileCount(1);
@@ -73,4 +82,50 @@ TEST_F(GeneralBrowserUsageUnitTest, ProfileCount) {
 }
 #endif  // !BUILDFLAG(IS_ANDROID)
 
+#if BUILDFLAG(IS_ANDROID) || BUILDFLAG(IS_WIN)
+TEST_F(GeneralBrowserUsageUnitTest, InstallTimeOff) {
+  base::Time install_time = base::Time::Now();
+  SetUpUsage(false, true, install_time);
+
+  histogram_tester_.ExpectUniqueSample(kDayZeroOffInstallTime, 0, 1);
+
+  task_environment_.FastForwardBy(base::Days(15));
+
+  histogram_tester_.ExpectBucketCount(kDayZeroOffInstallTime, 15, 1);
+  histogram_tester_.ExpectTotalCount(kDayZeroOnInstallTime, 0);
+
+  SetUpUsage(true, false, install_time);
+  // Ensure histogram name does not change if "day zero" is enabled
+  // after install; we only want to report the "day zero on" metric
+  // if it was enabled at install time.
+  histogram_tester_.ExpectBucketCount(kDayZeroOffInstallTime, 15, 2);
+  histogram_tester_.ExpectTotalCount(kDayZeroOnInstallTime, 0);
+
+  task_environment_.FastForwardBy(base::Days(15));
+  histogram_tester_.ExpectBucketCount(kDayZeroOffInstallTime, 30, 1);
+
+  // Ensure there are no more reports past 30 days
+  task_environment_.FastForwardBy(base::Days(5));
+
+  histogram_tester_.ExpectTotalCount(kDayZeroOffInstallTime, 32);
+  histogram_tester_.ExpectTotalCount(kDayZeroOnInstallTime, 0);
+}
+
+TEST_F(GeneralBrowserUsageUnitTest, InstallTimeOn) {
+  base::Time install_time = base::Time::Now();
+  SetUpUsage(true, true, install_time);
+
+  histogram_tester_.ExpectUniqueSample(kDayZeroOnInstallTime, 0, 1);
+
+  task_environment_.FastForwardBy(base::Days(15));
+
+  histogram_tester_.ExpectBucketCount(kDayZeroOnInstallTime, 15, 1);
+  histogram_tester_.ExpectTotalCount(kDayZeroOffInstallTime, 0);
+
+  SetUpUsage(false, false, install_time);
+  histogram_tester_.ExpectBucketCount(kDayZeroOnInstallTime, 15, 2);
+  histogram_tester_.ExpectTotalCount(kDayZeroOffInstallTime, 0);
+}
+#endif  // BUILDFLAG(IS_ANDROID) || BUILDFLAG(IS_WIN)
+
 }  // namespace misc_metrics

components/misc_metrics/pref_names.h

@@ -59,6 +59,9 @@ inline constexpr char kMiscMetricsNewTabLocationBarEntriesStorage[] =
     "brave.misc_metrics.new_tab_location_bar_entries_storage";
 inline constexpr char kMiscMetricsTotalLocationBarEntriesStorage[] =
     "brave.misc_metrics.total_location_bar_entries_storage";
+
+inline constexpr char kMiscMetricsDayZeroAtInstall[] =
+    "brave.misc_metrics.day_zero_at_install";
 }  // namespace misc_metrics
 
 #endif  // BRAVE_COMPONENTS_MISC_METRICS_PREF_NAMES_H_

components/p3a/metric_names.h

@@ -257,6 +257,8 @@ inline constexpr auto kCollectedExpressHistograms =
   base::MakeFixedFlatSet<std::string_view>(base::sorted_unique,{
     "Brave.AIChat.UsageDaily.2",
     "Brave.Core.UsageDaily",
+    "Brave.DayZero.Off.InstallTime",
+    "Brave.DayZero.On.InstallTime",
     "Brave.Rewards.EnabledInstallationTime",
     "Brave.Search.DefaultEngine.4",
     "Brave.Today.IsEnabled",
@@ -284,6 +286,8 @@ inline constexpr auto kEphemeralHistograms =
     "Brave.AIChat.UsageMonthly",
     "Brave.AIChat.UsageWeekly",
     "Brave.Core.FailedHTTPSUpgrades",
+    "Brave.DayZero.Off.InstallTime",
+    "Brave.DayZero.On.InstallTime",
     "Brave.Playlist.FirstTimeOffset",
     "Brave.Playlist.UsageDaysInWeek",
     "Brave.PrivacyHub.Views",
@@ -325,15 +329,16 @@ inline constexpr auto kEphemeralHistograms =
 inline constexpr auto kConstellationOnlyHistograms =
   base::MakeFixedFlatSet<std::string_view>(base::sorted_unique,{
     "Brave.Core.PrimaryLang",
+    "Brave.DayZero.Off.InstallTime",
+    "Brave.DayZero.On.InstallTime",
 });
 
 // List of metrics which will include the stored refcode when transmitted
 // via the STAR/Constellation protocol.
 inline constexpr auto kHistogramsWithRefcodeIncluded =
   base::MakeFixedFlatSet<std::string_view>(base::sorted_unique,{
-    // TODO(djandries): Replace this metric with the first metric
-    // to include a refcode.
-    "Brave.ExampleMetric"
+    "Brave.DayZero.Off.InstallTime",
+    "Brave.DayZero.On.InstallTime",
 });
 
 // clang-format on

components/p3a/star_randomness_test_util.cc

@@ -57,7 +57,8 @@ std::string HandleRandomnessRequest(const network::ResourceRequest& request,
   rust::Vec<constellation::VecU8> req_points_rust;
   const base::Value::List* points_list = req_parsed_val.FindList("points");
 
-  EXPECT_EQ(points_list->size(), 8U);
+  EXPECT_GE(points_list->size(), 8U);
+  EXPECT_LE(points_list->size(), 9U);
 
   std::transform(
       points_list->begin(), points_list->end(),
@@ -72,7 +73,8 @@ std::string HandleRandomnessRequest(const network::ResourceRequest& request,
   auto rand_result =
       constellation::generate_local_randomness(req_points_rust, expected_epoch);
 
-  EXPECT_EQ(rand_result.points.size(), 8U);
+  EXPECT_GE(rand_result.points.size(), 8U);
+  EXPECT_LE(rand_result.points.size(), 9U);
 
   base::Value::List resp_points_list;
   for (const constellation::VecU8& resp_point_rust : rand_result.points) {