Remove enhanced bookmarks sync experiment

Uses the enhanced bookmarks Finch experiment as the only mechanism for
enabling enhanced bookmarks in Chrome. With this change we no longer
need the EnhancedBookmarks.SyncExperimentState UMA histogram since we
can now get all the relevant metrics via Finch.

BUG=467040

Review URL: https://codereview.chromium.org/1009673002

Cr-Commit-Position: refs/heads/master@{#320973}

2 files changed, 22 insertions, 236 deletions

diff --git a/chrome/browser/bookmarks/enhanced_bookmarks_features.cc b/chrome/browser/bookmarks/enhanced_bookmarks_features.cc
index 142e5cb..9f681c6 100644
--- a/chrome/browser/bookmarks/enhanced_bookmarks_features.cc
+++ b/chrome/browser/bookmarks/enhanced_bookmarks_features.cc
@@ -30,200 +30,35 @@ namespace {
 
 const char kFieldTrialName[] = "EnhancedBookmarks";
 
-// Get extension id from Finch EnhancedBookmarks group parameters.
-std::string GetEnhancedBookmarksExtensionIdFromFinch() {
-  return variations::GetVariationParamValue(kFieldTrialName, "id");
-}
-
-// Returns true if enhanced bookmarks experiment is enabled from Finch.
-bool IsEnhancedBookmarksExperimentEnabledFromFinch() {
-  const std::string ext_id = GetEnhancedBookmarksExtensionIdFromFinch();
-#if defined(OS_ANDROID)
-  return !ext_id.empty();
-#else
-  const extensions::FeatureProvider* feature_provider =
-      extensions::FeatureProvider::GetPermissionFeatures();
-  extensions::Feature* feature = feature_provider->GetFeature("metricsPrivate");
-  return feature && feature->IsIdInWhitelist(ext_id);
-#endif
-}
-
-};  // namespace
+}  // namespace
 
-bool GetBookmarksExperimentExtensionID(const PrefService* user_prefs,
-                                       std::string* extension_id) {
-  BookmarksExperimentState bookmarks_experiment_state =
-      static_cast<BookmarksExperimentState>(user_prefs->GetInteger(
-          sync_driver::prefs::kEnhancedBookmarksExperimentEnabled));
-  if (bookmarks_experiment_state == BOOKMARKS_EXPERIMENT_ENABLED_FROM_FINCH) {
-    *extension_id = GetEnhancedBookmarksExtensionIdFromFinch();
-    return !extension_id->empty();
-  }
-  if (bookmarks_experiment_state == BOOKMARKS_EXPERIMENT_ENABLED) {
-    *extension_id = user_prefs->GetString(
-        sync_driver::prefs::kEnhancedBookmarksExtensionId);
-    return !extension_id->empty();
-  }
-
-  return false;
-}
-
-void UpdateBookmarksExperimentState(
-    PrefService* user_prefs,
-    PrefService* local_state,
-    bool user_signed_in,
-    BookmarksExperimentState experiment_enabled_from_sync) {
- PrefService* flags_storage = local_state;
-#if defined(OS_CHROMEOS)
-  // Chrome OS is using user prefs for flags storage.
-  flags_storage = user_prefs;
-#endif
-
-  BookmarksExperimentState bookmarks_experiment_state_before =
-      static_cast<BookmarksExperimentState>(user_prefs->GetInteger(
-          sync_driver::prefs::kEnhancedBookmarksExperimentEnabled));
-  // If user signed out, clear possible previous state.
-  if (!user_signed_in) {
-    bookmarks_experiment_state_before = BOOKMARKS_EXPERIMENT_NONE;
-    ForceFinchBookmarkExperimentIfNeeded(flags_storage,
-        BOOKMARKS_EXPERIMENT_NONE);
-  }
+bool GetBookmarksExperimentExtensionID(std::string* extension_id) {
+  *extension_id = variations::GetVariationParamValue(kFieldTrialName, "id");
+  if (extension_id->empty())
+    return false;
 
   // kEnhancedBookmarksExperiment flag could have values "", "1" and "0".
   // "0" - user opted out.
   bool opt_out = base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
-                     switches::kEnhancedBookmarksExperiment) == "0";
+      switches::kEnhancedBookmarksExperiment) == "0";
 
-  BookmarksExperimentState bookmarks_experiment_new_state =
-      BOOKMARKS_EXPERIMENT_NONE;
-
-  if (IsEnhancedBookmarksExperimentEnabledFromFinch() && !user_signed_in) {
-    if (opt_out) {
-      // Experiment enabled but user opted out.
-      bookmarks_experiment_new_state = BOOKMARKS_EXPERIMENT_OPT_OUT_FROM_FINCH;
-    } else {
-      // Experiment enabled.
-      bookmarks_experiment_new_state = BOOKMARKS_EXPERIMENT_ENABLED_FROM_FINCH;
-    }
-  } else if (experiment_enabled_from_sync == BOOKMARKS_EXPERIMENT_ENABLED) {
-    // Experiment enabled from Chrome sync.
-    if (opt_out) {
-      // Experiment enabled but user opted out.
-      bookmarks_experiment_new_state =
-          BOOKMARKS_EXPERIMENT_ENABLED_USER_OPT_OUT;
-    } else {
-      // Experiment enabled.
-      bookmarks_experiment_new_state = BOOKMARKS_EXPERIMENT_ENABLED;
-    }
-  } else if (experiment_enabled_from_sync == BOOKMARKS_EXPERIMENT_NONE) {
-    // Experiment is not enabled from Chrome sync.
-    bookmarks_experiment_new_state = BOOKMARKS_EXPERIMENT_NONE;
-  } else if (bookmarks_experiment_state_before ==
-             BOOKMARKS_EXPERIMENT_ENABLED) {
-    if (opt_out) {
-      // Experiment enabled but user opted out.
-      bookmarks_experiment_new_state =
-          BOOKMARKS_EXPERIMENT_ENABLED_USER_OPT_OUT;
-    } else {
-      bookmarks_experiment_new_state = BOOKMARKS_EXPERIMENT_ENABLED;
-    }
-  } else if (bookmarks_experiment_state_before ==
-             BOOKMARKS_EXPERIMENT_ENABLED_USER_OPT_OUT) {
-    if (opt_out) {
-      bookmarks_experiment_new_state =
-          BOOKMARKS_EXPERIMENT_ENABLED_USER_OPT_OUT;
-    } else {
-      // User opted in again.
-      bookmarks_experiment_new_state = BOOKMARKS_EXPERIMENT_ENABLED;
-    }
-  }
+  if (opt_out)
+    return false;
 
 #if defined(OS_ANDROID)
-  if (base::android::BuildInfo::GetInstance()->sdk_int() <=
-      base::android::SdkVersion::SDK_VERSION_ICE_CREAM_SANDWICH_MR1) {
-    opt_out = true;
-    bookmarks_experiment_new_state = BOOKMARKS_EXPERIMENT_NONE;
-  }
-  bool opt_in = !opt_out &&
-                base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
-                    switches::kEnhancedBookmarksExperiment) == "1";
-  if (opt_in && bookmarks_experiment_new_state == BOOKMARKS_EXPERIMENT_NONE)
-    bookmarks_experiment_new_state = BOOKMARKS_EXPERIMENT_ENABLED;
-#endif
-
-  UMA_HISTOGRAM_ENUMERATION("EnhancedBookmarks.SyncExperimentState",
-                            bookmarks_experiment_new_state,
-                            BOOKMARKS_EXPERIMENT_ENUM_SIZE);
-  user_prefs->SetInteger(
-      sync_driver::prefs::kEnhancedBookmarksExperimentEnabled,
-      bookmarks_experiment_new_state);
-  ForceFinchBookmarkExperimentIfNeeded(flags_storage,
-                                       bookmarks_experiment_new_state);
-}
-
-void InitBookmarksExperimentState(Profile* profile) {
-  SigninManagerBase* signin = SigninManagerFactory::GetForProfile(profile);
-  bool is_signed_in = signin && signin->IsAuthenticated();
-  UpdateBookmarksExperimentState(
-      profile->GetPrefs(),
-      g_browser_process->local_state(),
-      is_signed_in,
-      BOOKMARKS_EXPERIMENT_ENABLED_FROM_SYNC_UNKNOWN);
-}
-
-void ForceFinchBookmarkExperimentIfNeeded(
-    PrefService* flags_storage,
-    BookmarksExperimentState bookmarks_experiment_state) {
-  if (!flags_storage)
-    return;
-  ListPrefUpdate update(flags_storage, prefs::kEnabledLabsExperiments);
-  base::ListValue* experiments_list = update.Get();
-  if (!experiments_list)
-    return;
-  size_t index;
-  if (bookmarks_experiment_state == BOOKMARKS_EXPERIMENT_NONE) {
-    experiments_list->Remove(
-        base::StringValue(switches::kManualEnhancedBookmarks), &index);
-    experiments_list->Remove(
-        base::StringValue(switches::kManualEnhancedBookmarksOptout), &index);
-  } else if (bookmarks_experiment_state == BOOKMARKS_EXPERIMENT_ENABLED) {
-    experiments_list->Remove(
-        base::StringValue(switches::kManualEnhancedBookmarksOptout), &index);
-    experiments_list->AppendIfNotPresent(
-        new base::StringValue(switches::kManualEnhancedBookmarks));
-  } else if (bookmarks_experiment_state ==
-                 BOOKMARKS_EXPERIMENT_ENABLED_USER_OPT_OUT) {
-    experiments_list->Remove(
-        base::StringValue(switches::kManualEnhancedBookmarks), &index);
-    experiments_list->AppendIfNotPresent(
-        new base::StringValue(switches::kManualEnhancedBookmarksOptout));
-  }
-}
-
-bool IsEnhancedBookmarksExperimentEnabled(
-    about_flags::FlagsStorage* flags_storage) {
-#if defined(OS_CHROMEOS)
-  // We are not setting command line flags on Chrome OS to avoid browser restart
-  // but still have flags in flags_storage. So check flags_storage instead.
-  const std::set<std::string> flags = flags_storage->GetFlags();
-  if (flags.find(switches::kManualEnhancedBookmarks) != flags.end())
-    return true;
-  if (flags.find(switches::kManualEnhancedBookmarksOptout) != flags.end())
-    return true;
+  return base::android::BuildInfo::GetInstance()->sdk_int() >
+         base::android::SdkVersion::SDK_VERSION_ICE_CREAM_SANDWICH_MR1;
 #else
-  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
-  if (command_line->HasSwitch(switches::kManualEnhancedBookmarks) ||
-      command_line->HasSwitch(switches::kManualEnhancedBookmarksOptout)) {
-    return true;
-  }
+  const extensions::FeatureProvider* feature_provider =
+      extensions::FeatureProvider::GetPermissionFeatures();
+  extensions::Feature* feature = feature_provider->GetFeature("metricsPrivate");
+  return feature && feature->IsIdInWhitelist(*extension_id);
 #endif
-
-  return IsEnhancedBookmarksExperimentEnabledFromFinch();
 }
 
 #if defined(OS_ANDROID)
 bool IsEnhancedBookmarkImageFetchingEnabled(const PrefService* user_prefs) {
-  if (IsEnhancedBookmarksEnabled(user_prefs))
+  if (IsEnhancedBookmarksEnabled())
     return true;
 
   // Salient images are collected from visited bookmarked pages even if the
@@ -236,12 +71,9 @@ bool IsEnhancedBookmarkImageFetchingEnabled(const PrefService* user_prefs) {
   return disable_fetching.empty();
 }
 
-bool IsEnhancedBookmarksEnabled(const PrefService* user_prefs) {
-  BookmarksExperimentState bookmarks_experiment_state =
-      static_cast<BookmarksExperimentState>(user_prefs->GetInteger(
-          sync_driver::prefs::kEnhancedBookmarksExperimentEnabled));
-  return bookmarks_experiment_state == BOOKMARKS_EXPERIMENT_ENABLED ||
-      bookmarks_experiment_state == BOOKMARKS_EXPERIMENT_ENABLED_FROM_FINCH;
+bool IsEnhancedBookmarksEnabled() {
+  std::string extension_id;
+  return GetBookmarksExperimentExtensionID(&extension_id);
 }
 #endif
 
diff --git a/chrome/browser/bookmarks/enhanced_bookmarks_features.h b/chrome/browser/bookmarks/enhanced_bookmarks_features.h
index 7faf6bc..8e6a987 100644
--- a/chrome/browser/bookmarks/enhanced_bookmarks_features.h
+++ b/chrome/browser/bookmarks/enhanced_bookmarks_features.h
@@ -9,57 +9,11 @@
 
 #include "build/build_config.h"
 
-namespace about_flags {
-class FlagsStorage;
-}  // namespace about_flags
-
 class PrefService;
-class Profile;
-
-// States for bookmark experiment. They are set by Chrome sync into
-// sync_driver::prefs::kEnhancedBookmarksExperimentEnabled user preference and
-// used for UMA reporting as well.
-enum BookmarksExperimentState {
-  BOOKMARKS_EXPERIMENT_NONE,
-  BOOKMARKS_EXPERIMENT_ENABLED,
-  BOOKMARKS_EXPERIMENT_ENABLED_USER_OPT_OUT,
-  BOOKMARKS_EXPERIMENT_ENABLED_FROM_FINCH,
-  BOOKMARKS_EXPERIMENT_OPT_OUT_FROM_FINCH,
-  BOOKMARKS_EXPERIMENT_ENABLED_FROM_FINCH_USER_SIGNEDIN,
-  BOOKMARKS_EXPERIMENT_ENABLED_FROM_SYNC_UNKNOWN,
-  BOOKMARKS_EXPERIMENT_ENUM_SIZE
-};
-
-// Returns true and sets |extension_id| if bookmarks experiment enabled
-//         false if no bookmark experiment or extension id is empty.
-bool GetBookmarksExperimentExtensionID(const PrefService* user_prefs,
-                                       std::string* extension_id);
-
-// Updates bookmark experiment state based on information from Chrome sync,
-// Finch experiments, and command line flag.
-void UpdateBookmarksExperimentState(
-    PrefService* user_prefs,
-    PrefService* local_state,
-    bool user_signed_in,
-    BookmarksExperimentState experiment_enabled_from_sync);
-
-// Same as UpdateBookmarksExperimentState, but the last argument with
-// BOOKMARKS_EXPERIMENT_ENABLED_FROM_SYNC_UNKNOWN.
-// Intended for performing initial configuration of bookmarks experiments
-// when the browser is first initialized.
-void InitBookmarksExperimentState(Profile* profile);
-
-// Sets flag to opt-in user into Finch experiment.
-void ForceFinchBookmarkExperimentIfNeeded(
-    PrefService* local_state,
-    BookmarksExperimentState bookmarks_experiment_state);
 
-// Returns true if enhanced bookmarks experiment is running.
-// Experiment could run by Chrome sync or by Finch.
-// Note that this doesn't necessarily mean that enhanced bookmarks
-// is enabled, e.g., user can opt out using a flag.
-bool IsEnhancedBookmarksExperimentEnabled(
-    about_flags::FlagsStorage* flags_storage);
+// Returns true and sets |extension_id| if enhanced bookmarks experiment is
+// enabled. Returns false if no bookmark experiment or extension id is empty.
+bool GetBookmarksExperimentExtensionID(std::string* extension_id);
 
 #if defined(OS_ANDROID)
 // Returns true if enhanced bookmark salient image prefetching is enabled.
@@ -67,7 +21,7 @@ bool IsEnhancedBookmarksExperimentEnabled(
 bool IsEnhancedBookmarkImageFetchingEnabled(const PrefService* user_prefs);
 
 // Returns true if enhanced bookmarks is enabled.
-bool IsEnhancedBookmarksEnabled(const PrefService* user_prefs);
+bool IsEnhancedBookmarksEnabled();
 
 #endif