Revert "Sync cleanup: Remove DEPRECATED_EXPERIMENTS ModelType"

This reverts commit df3250dd.

Reason for revert: Suspected of causing crashes, see crbug.com/1047879

Original change's description:
> Sync cleanup: Remove DEPRECATED_EXPERIMENTS ModelType
> 
> It has been deprecated and unused for a while.
> The specifics proto itself can't be removed yet because it's still used
> on the server.
> 
> Bug: 1009361
> Change-Id: Ic183a6e244435cfce60ccdda34bff3e22a032ff3
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2022670
> Commit-Queue: Marc Treib <treib@chromium.org>
> Reviewed-by: Jan Krcal <jkrcal@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#736397}

TBR=treib@chromium.org,jkrcal@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 1009361, 1047879
Change-Id: I762fbf6f1b4b752a47b34e6a101a066d0c78aebc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2036005Reviewed-by: Marc Treib <treib@chromium.org>
Commit-Queue: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/master@{#738205}

chrome/browser/sync/profile_sync_service_factory_unittest.cc

@@ -55,7 +55,7 @@ class ProfileSyncServiceFactoryTest : public testing::Test {
 
   // Returns the collection of default datatypes.
   std::vector<syncer::ModelType> DefaultDatatypes() {
-    static_assert(40 == syncer::ModelType::NUM_ENTRIES,
+    static_assert(41 == syncer::ModelType::NUM_ENTRIES,
                   "When adding a new type, you probably want to add it here as "
                   "well (assuming it is already enabled).");
 

components/sync/PRESUBMIT.py

@@ -24,8 +24,10 @@ EXCEPTION_MODEL_TYPES = [
   'NIGORI',  # Model type string is 'encryption keys'.
   'SUPERVISED_USER_SETTINGS',  # Root tag and model type string replace
                                # 'Supervised' with 'Managed'
-  'SUPERVISED_USER_WHITELISTS'  # See previous.
-]
+  'SUPERVISED_USER_WHITELISTS',  # See previous.
+
+  # Deprecated types:
+  'DEPRECATED_EXPERIMENTS']
 
 # Root tags are used as prefixes when creating storage keys, so certain strings
 # are blacklisted in order to prevent prefix collision.

components/sync/PRESUBMIT_test.py

@@ -112,6 +112,12 @@ class ModelTypeInfoChangeTest(unittest.TestCase):
     results = self._testChange('{PROXY_TABS, "", "", "Tabs", -1, 25},')
     self.assertEqual(0, len(results))
 
+  def testValidChangeDeprecatedEntry(self):
+    results = self._testChange('{DEPRECATED_EXPERIMENTS, "EXPERIMENTS",'
+      '"experiments", "Experiments",'
+      'sync_pb::EntitySpecifics::kExperimentsFieldNumber, 19},')
+    self.assertEqual(0, len(results))
+
   def testInvalidChangeMismatchedNotificationType(self):
     results = self._testChange('{AUTOFILL, "AUTOFILL_WRONG", "autofill",\n'
      '"Autofill",sync_pb::EntitySpecifics::kAutofillFieldNumber, 6},')

components/sync/base/model_type.cc

@@ -181,16 +181,19 @@ const ModelTypeInfo kModelTypeInfoMap[] = {
     {NIGORI, "NIGORI", "nigori", "Encryption Keys",
      sync_pb::EntitySpecifics::kNigoriFieldNumber,
      ModelTypeForHistograms::kNigori},
+    {DEPRECATED_EXPERIMENTS, "EXPERIMENTS", "experiments", "Experiments",
+     sync_pb::EntitySpecifics::kExperimentsFieldNumber,
+     ModelTypeForHistograms::kDeprecatedExperiments},
 };
 
 static_assert(base::size(kModelTypeInfoMap) == ModelType::NUM_ENTRIES,
               "kModelTypeInfoMap should have ModelType::NUM_ENTRIES elements");
 
-static_assert(40 == syncer::ModelType::NUM_ENTRIES,
+static_assert(41 == syncer::ModelType::NUM_ENTRIES,
               "When adding a new type, update enum SyncModelTypes in enums.xml "
               "and suffix SyncModelType in histograms.xml.");
 
-static_assert(40 == syncer::ModelType::NUM_ENTRIES,
+static_assert(41 == syncer::ModelType::NUM_ENTRIES,
               "When adding a new type, update kAllocatorDumpNameWhitelist in "
               "base/trace_event/memory_infra_background_whitelist.cc.");
 
@@ -299,6 +302,9 @@ void AddDefaultFieldValue(ModelType type, sync_pb::EntitySpecifics* specifics) {
     case NIGORI:
       specifics->mutable_nigori();
       break;
+    case DEPRECATED_EXPERIMENTS:
+      specifics->mutable_experiments();
+      break;
     case WEB_APPS:
       specifics->mutable_web_app();
       break;
@@ -356,7 +362,7 @@ ModelType GetModelType(const sync_pb::SyncEntity& sync_entity) {
 }
 
 ModelType GetModelTypeFromSpecifics(const sync_pb::EntitySpecifics& specifics) {
-  static_assert(40 == ModelType::NUM_ENTRIES,
+  static_assert(41 == ModelType::NUM_ENTRIES,
                 "When adding new protocol types, the following type lookup "
                 "logic must be updated.");
   if (specifics.has_bookmark())
@@ -419,6 +425,8 @@ ModelType GetModelTypeFromSpecifics(const sync_pb::EntitySpecifics& specifics) {
     return USER_CONSENTS;
   if (specifics.has_nigori())
     return NIGORI;
+  if (specifics.has_experiments())
+    return DEPRECATED_EXPERIMENTS;
   if (specifics.has_send_tab_to_self())
     return SEND_TAB_TO_SELF;
   if (specifics.has_security_event())
@@ -438,7 +446,7 @@ ModelType GetModelTypeFromSpecifics(const sync_pb::EntitySpecifics& specifics) {
 }
 
 ModelTypeSet EncryptableUserTypes() {
-  static_assert(40 == ModelType::NUM_ENTRIES,
+  static_assert(41 == ModelType::NUM_ENTRIES,
                 "If adding an unencryptable type, remove from "
                 "encryptable_user_types below.");
   ModelTypeSet encryptable_user_types = UserTypes();

components/sync/base/model_type.h

@@ -154,7 +154,8 @@ enum ModelType {
   // ---- Control Types ----
   // An object representing a set of Nigori keys.
   NIGORI,
-  LAST_REAL_MODEL_TYPE = NIGORI,
+  DEPRECATED_EXPERIMENTS,
+  LAST_REAL_MODEL_TYPE = DEPRECATED_EXPERIMENTS,
 
   NUM_ENTRIES,
 };
@@ -199,7 +200,7 @@ enum class ModelTypeForHistograms {
   kHistoryDeleteDirectices = 16,
   kNigori = 17,
   kDeviceInfo = 18,
-  // kDeprecatedExperiments = 19,
+  kDeprecatedExperiments = 19,
   // kDeprecatedSyncedNotifications = 20,
   kPriorityPreferences = 21,
   kDictionary = 22,
@@ -257,9 +258,10 @@ constexpr ModelTypeSet ProtocolTypes() {
       EXTENSION_SETTINGS, HISTORY_DELETE_DIRECTIVES, DICTIONARY, FAVICON_IMAGES,
       FAVICON_TRACKING, DEVICE_INFO, PRIORITY_PREFERENCES,
       SUPERVISED_USER_SETTINGS, APP_LIST, SUPERVISED_USER_WHITELISTS,
-      ARC_PACKAGE, PRINTERS, READING_LIST, USER_EVENTS, NIGORI, USER_CONSENTS,
-      SEND_TAB_TO_SELF, SECURITY_EVENTS, WEB_APPS, WIFI_CONFIGURATIONS,
-      OS_PREFERENCES, OS_PRIORITY_PREFERENCES, SHARING_MESSAGE);
+      ARC_PACKAGE, PRINTERS, READING_LIST, USER_EVENTS, NIGORI,
+      DEPRECATED_EXPERIMENTS, USER_CONSENTS, SEND_TAB_TO_SELF, SECURITY_EVENTS,
+      WEB_APPS, WIFI_CONFIGURATIONS, OS_PREFERENCES, OS_PRIORITY_PREFERENCES,
+      SHARING_MESSAGE);
 }
 
 // These are the normal user-controlled types. This is to distinguish from

components/sync/driver/model_association_manager.cc

@@ -29,6 +29,7 @@ namespace {
 static const ModelType kStartOrder[] = {
     NIGORI,  //  Listed for completeness.
     DEVICE_INFO,
+    DEPRECATED_EXPERIMENTS,  //  Listed for completeness.
     PROXY_TABS,              //  Listed for completeness.
 
     // Kick off the association of the non-UI types first so they can associate

components/sync/driver/profile_sync_service.cc

@@ -1461,7 +1461,7 @@ ModelTypeSet ProfileSyncService::GetModelTypesForTransportOnlyMode() const {
   }
 
   // Outside the #if so non-Chrome OS developers will hit it before uploading.
-  static_assert(40 == ModelType::NUM_ENTRIES,
+  static_assert(41 == ModelType::NUM_ENTRIES,
                 "If a new ModelType is Chrome OS-only and uses OS sync "
                 "consent, add it below.");
 #if defined(OS_CHROMEOS)

components/sync/driver/sync_user_settings_impl.cc

@@ -241,7 +241,7 @@ ModelTypeSet SyncUserSettingsImpl::GetPreferredDataTypes() const {
 #endif
   types.RetainAll(registered_model_types_);
 
-  static_assert(40 == ModelType::NUM_ENTRIES,
+  static_assert(41 == ModelType::NUM_ENTRIES,
                 "If adding a new sync data type, update the list below below if"
                 " you want to disable the new data type for local sync.");
   types.PutAll(ControlTypes());

components/sync/nigori/nigori_state.cc

@@ -61,7 +61,7 @@ bool EncryptKeyBag(const CryptographerImpl& cryptographer,
 void UpdateNigoriSpecificsFromEncryptedTypes(
     ModelTypeSet encrypted_types,
     sync_pb::NigoriSpecifics* specifics) {
-  static_assert(40 == ModelType::NUM_ENTRIES,
+  static_assert(41 == ModelType::NUM_ENTRIES,
                 "If adding an encryptable type, update handling below.");
   specifics->set_encrypt_bookmarks(encrypted_types.Has(BOOKMARKS));
   specifics->set_encrypt_preferences(encrypted_types.Has(PREFERENCES));

components/sync/protocol/proto_value_conversions_unittest.cc

@@ -59,7 +59,7 @@ namespace {
 
 DEFINE_SPECIFICS_TO_VALUE_TEST(encrypted)
 
-static_assert(40 == syncer::ModelType::NUM_ENTRIES,
+static_assert(41 == syncer::ModelType::NUM_ENTRIES,
               "When adding a new field, add a DEFINE_SPECIFICS_TO_VALUE_TEST "
               "for your field below, and optionally a test for the specific "
               "conversions.");

components/sync/protocol/proto_visitors.h

@@ -370,7 +370,7 @@ VISIT_PROTO_FIELDS(const sync_pb::EntityMetadata& proto) {
 }
 
 VISIT_PROTO_FIELDS(const sync_pb::EntitySpecifics& proto) {
-  static_assert(40 == ModelType::NUM_ENTRIES,
+  static_assert(41 == ModelType::NUM_ENTRIES,
                 "When adding a new protocol type, you will likely need to add "
                 "it here as well.");
   VISIT(encrypted);

components/sync/syncable/nigori_util.cc

@@ -265,7 +265,7 @@ void UpdateNigoriFromEncryptedTypes(ModelTypeSet encrypted_types,
                                     bool encrypt_everything,
                                     sync_pb::NigoriSpecifics* nigori) {
   nigori->set_encrypt_everything(encrypt_everything);
-  static_assert(40 == ModelType::NUM_ENTRIES,
+  static_assert(41 == ModelType::NUM_ENTRIES,
                 "If adding an encryptable type, update handling below.");
   nigori->set_encrypt_bookmarks(encrypted_types.Has(BOOKMARKS));
   nigori->set_encrypt_preferences(encrypted_types.Has(PREFERENCES));
@@ -300,7 +300,7 @@ ModelTypeSet GetEncryptedTypesFromNigori(
     return ModelTypeSet::All();
 
   ModelTypeSet encrypted_types;
-  static_assert(40 == ModelType::NUM_ENTRIES,
+  static_assert(41 == ModelType::NUM_ENTRIES,
                 "If adding an encryptable type, update handling below.");
   if (nigori.encrypt_bookmarks())
     encrypted_types.Put(BOOKMARKS);

ios/chrome/browser/sync/profile_sync_service_factory_unittest.cc

@@ -43,7 +43,7 @@ class ProfileSyncServiceFactoryTest : public PlatformTest {
  protected:
   // Returns the collection of default datatypes.
   std::vector<syncer::ModelType> DefaultDatatypes() {
-    static_assert(40 == syncer::ModelType::NUM_ENTRIES,
+    static_assert(41 == syncer::ModelType::NUM_ENTRIES,
                   "When adding a new type, you probably want to add it here as "
                   "well (assuming it is already enabled).");