Navi: populate synthetic trials.

Once a local profile enters a synthetic trial for on-boarding, it will
remain in it forever. This is not a problem because local profiles
should not be running the on-boarding process more than once. If a user
creates a new profile, it will be assigned into a synthetic trial based
on the experiment at the time of onboarding.

Bug: 874153
Change-Id: I4f3b9aea39e75fd01ae7dabd7895ea8aa00e633a
Reviewed-on: https://chromium-review.googlesource.com/c/1344990
Commit-Queue: Hector Carmona <hcarmona@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Cr-Commit-Position: refs/heads/master@{#612364}

chrome/browser/metrics/chrome_metrics_service_accessor.h

@@ -66,6 +66,10 @@ namespace heap_profiling {
 class BackgroundProfilingTriggers;
 }
 
+namespace nux {
+bool IsNuxOnboardingEnabled(Profile* profile);
+}
+
 namespace safe_browsing {
 class ChromeCleanerControllerDelegate;
 class DownloadUrlSBClient;
@@ -141,6 +145,7 @@ class ChromeMetricsServiceAccessor : public metrics::MetricsServiceAccessor {
   friend class ChromePasswordManagerClient;
   friend class NavigationMetricsRecorder;
   friend class ChromeUnifiedConsentServiceClient;
+  friend bool nux::IsNuxOnboardingEnabled(Profile* profile);
 
   // Testing related friends.
   friend class MetricsReportingStateTest;

chrome/browser/prefs/browser_prefs.cc

@@ -384,6 +384,7 @@ const char kReverseAutologinEnabled[] = "reverse_autologin.enabled";
 const char kNetworkQualities[] = "net.network_qualities";
 const char kForceSessionSync[] = "settings.history_recorded";
 const char kOnboardDuringNUX[] = "browser.onboard_during_nux";
+const char kNuxOnboardGroup[] = "browser.onboard_group";
 // This pref is particularly large, taking up 15+% of the prefs file, so should
 // perhaps be kept around longer than the others.
 const char kHttpServerProperties[] = "net.http_server_properties";
@@ -417,6 +418,7 @@ void RegisterProfilePrefsForMigration(
   registry->RegisterDictionaryPref(kNetworkQualities, PrefRegistry::LOSSY_PREF);
   registry->RegisterBooleanPref(kForceSessionSync, false);
   registry->RegisterBooleanPref(kOnboardDuringNUX, false);
+  registry->RegisterIntegerPref(kNuxOnboardGroup, 0);
   registry->RegisterDictionaryPref(kHttpServerProperties,
                                    PrefRegistry::LOSSY_PREF);
 }
@@ -886,5 +888,6 @@ void MigrateObsoleteProfilePrefs(Profile* profile) {
   profile_prefs->ClearPref(kNetworkQualities);
   profile_prefs->ClearPref(kForceSessionSync);
   profile_prefs->ClearPref(kOnboardDuringNUX);
+  profile_prefs->ClearPref(kNuxOnboardGroup);
   profile_prefs->ClearPref(kHttpServerProperties);
 }

chrome/browser/profiles/profile_manager.cc

@@ -1081,8 +1081,8 @@ void ProfileManager::InitProfileUserPrefs(Profile* profile) {
 #if defined(OS_WIN) && defined(GOOGLE_CHROME_BUILD)
     // Enterprise users should not be included in any NUX/Navi flow.
     if (!base::win::IsEnterpriseManaged()) {
-      int group = nux::GetOnboardingGroup();
-      profile->GetPrefs()->SetInteger(prefs::kNuxOnboardGroup, group);
+      profile->GetPrefs()->SetString(prefs::kNaviOnboardGroup,
+                                     nux::GetOnboardingGroup());
     }
 #endif  // defined(OS_WIN) && defined(GOOGLE_CHROME_BUILD)
   }

chrome/browser/ui/startup/startup_browser_creator.cc

@@ -470,9 +470,9 @@ void StartupBrowserCreator::RegisterProfilePrefs(PrefRegistrySimple* registry) {
   // creation.
   registry->RegisterBooleanPref(prefs::kHasSeenWelcomePage, true);
 #if defined(OS_WIN) && defined(GOOGLE_CHROME_BUILD)
-  // This will be set to a group number for newly created profiles, and is used
-  // to indicate which users went through onboarding with the current group.
-  registry->RegisterIntegerPref(prefs::kNuxOnboardGroup, 0);
+  // This will be set for newly created profiles, and is used to indicate which
+  // users went through onboarding with the current experiment group.
+  registry->RegisterStringPref(prefs::kNaviOnboardGroup, "");
 #endif  // defined(OS_WIN) && defined(GOOGLE_CHROME_BUILD)
 }
 

chrome/browser/ui/webui/welcome/nux_helper.cc

@@ -7,9 +7,11 @@
 #include <string>
 
 #include "base/feature_list.h"
+#include "base/metrics/field_trial.h"
 #include "base/metrics/field_trial_params.h"
 #include "base/values.h"
 #include "build/build_config.h"
+#include "chrome/browser/metrics/chrome_metrics_service_accessor.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/webui/welcome/nux/constants.h"
 #include "chrome/common/pref_names.h"
@@ -34,11 +36,15 @@ const base::FeatureParam<std::string>
 const base::FeatureParam<bool> kNuxOnboardingForceEnabledShowEmailInterstitial =
     {&kNuxOnboardingForceEnabled, "show-email-interstitial", true};
 
-int GetOnboardingGroup() {
-  // Preppend a 0 to avoid issues with empty string.
-  return std::stoi("0" + base::GetFieldTrialParamValue(
-                             /* Must match finch study name */ "NaviOnboarding",
-                             "onboarding-group"));
+// Must match study name in configs.
+const char kNuxOnboardingStudyName[] = "NaviOnboarding";
+
+std::string GetOnboardingGroup() {
+  // We need to use |base::GetFieldTrialParamValue| instead of
+  // |base::FeatureParam| because our control group needs a custom value for
+  // this param.
+  return base::GetFieldTrialParamValue(kNuxOnboardingStudyName,
+                                       "onboarding-group");
 }
 
 bool IsNuxOnboardingEnabled(Profile* profile) {
@@ -47,23 +53,21 @@ bool IsNuxOnboardingEnabled(Profile* profile) {
   } else {
 #if defined(OS_WIN) && defined(GOOGLE_CHROME_BUILD)
     // To avoid diluting data collection, existing users should not be assigned
-    // an NUX group. So, the kNuxOnboardGroup integer is used to short-circuit
-    // the feature checks below.
+    // an onboarding group. So, |prefs::kNaviOnboardGroup| is used to
+    // short-circuit the feature checks below.
     PrefService* prefs = profile->GetPrefs();
     if (!prefs)
       return false;
 
-    int onboard_group = prefs->GetInteger(prefs::kNuxOnboardGroup);
+    std::string onboard_group = prefs->GetString(prefs::kNaviOnboardGroup);
 
-    if (onboard_group == 0)
+    if (onboard_group.empty())
       return false;
 
-    int current_group = GetOnboardingGroup();
-    if (onboard_group != current_group) {
-      // Remove user from group if they're not part of the current experiment.
-      prefs->SetInteger(prefs::kNuxOnboardGroup, 0);
-      return false;
-    }
+    // User will be tied to their original onboarding group, even after
+    // experiment ends.
+    ChromeMetricsServiceAccessor::RegisterSyntheticFieldTrial(
+        kNuxOnboardingStudyName, onboard_group);
 
     return base::FeatureList::IsEnabled(nux::kNuxOnboardingFeature);
 #else
@@ -85,7 +89,7 @@ base::DictionaryValue GetNuxOnboardingModules(Profile* profile) {
                       kNuxOnboardingForceEnabledReturningUserModules.Get());
     modules.SetBoolean("show-email-interstitial",
                        kNuxOnboardingForceEnabledShowEmailInterstitial.Get());
-  } else {  // This means nux::kNuxOnboardingFeature is enabled.
+  } else {  // This means |nux::kNuxOnboardingFeature| is enabled.
     modules.SetString("new-user", kNuxOnboardingNewUserModules.Get());
     modules.SetString("returning-user",
                       kNuxOnboardingReturningUserModules.Get());

chrome/browser/ui/webui/welcome/nux_helper.h

@@ -5,6 +5,8 @@
 #ifndef CHROME_BROWSER_UI_WEBUI_WELCOME_NUX_HELPER_H_
 #define CHROME_BROWSER_UI_WEBUI_WELCOME_NUX_HELPER_H_
 
+#include <string>
+
 #include "base/macros.h"
 #include "base/metrics/field_trial_params.h"
 
@@ -25,14 +27,14 @@ extern const base::FeatureParam<std::string>
 extern const base::FeatureParam<bool>
     kNuxOnboardingForceEnabledShowEmailInterstitial;
 
-// Get the group number for users who onboard in this experiment.
+// Get the group for users who onboard in this experiment.
 // Groups are:
-//   - Specified by finch
-//   - The same for all experiments in finch
+//   - Specified by study
+//   - The same for all experiments in study
 //   - Incremented with each new version
 //   - Not reused
 //   - Cleared out when experiment ends
-int GetOnboardingGroup();
+std::string GetOnboardingGroup();
 
 bool IsNuxOnboardingEnabled(Profile* profile);
 

chrome/common/pref_names.cc

@@ -1295,7 +1295,7 @@ const char kHasSeenWin10PromoPage[] = "browser.has_seen_win10_promo_page";
 // Put the user into an onboarding group that's decided when they go through
 // the first run onboarding experience. Only users in a group will have their
 // finch group pinged to keep track of them for the experiment.
-const char kNuxOnboardGroup[] = "browser.onboard_group";
+const char kNaviOnboardGroup[] = "browser.navi_onboard_group";
 #endif  // defined(GOOGLE_CHROME_BUILD)
 #endif  // defined(OS_WIN)
 

chrome/common/pref_names.h

@@ -442,7 +442,7 @@ extern const char kHasSeenWelcomePage[];
 #if defined(OS_WIN)
 extern const char kHasSeenWin10PromoPage[];
 #if defined(GOOGLE_CHROME_BUILD)
-extern const char kNuxOnboardGroup[];
+extern const char kNaviOnboardGroup[];
 #endif  // defined(GOOGLE_CHROME_BUILD)
 #endif  // defined(OS_WIN)