Add plumbing and sync integration tests for pseudo-USS

A USS bridge has been recently introduced in
https://chromium-review.googlesource.com/c/chromium/src/+/1164742 to
allow integrating legacy SyncableService sync datatypes into the most
modern USS architecture.

In this patch, a controller is introduced to do the necessary plumbing
and use the new codepath behind feature toggles. We do this for a first
set of datatypes that are simplest, i.e. the ones that live in the UI
thread and without complex logic in their controllers. Follow-up
patches will add support for more.

Bug: 870624
Change-Id: Ibdcc01133103296bd9c53e165a37b63cc32dcb87
Reviewed-on: https://chromium-review.googlesource.com/1251102Reviewed-by: Marc Treib <treib@chromium.org>
Commit-Queue: Mikel Astiz <mastiz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#595036}

chrome/browser/BUILD.gn

@@ -2927,6 +2927,8 @@ jumbo_split_static_library("browser") {
       "status_icons/desktop_notification_balloon.h",
       "sync/glue/extension_data_type_controller.cc",
       "sync/glue/extension_data_type_controller.h",
+      "sync/glue/extension_model_type_controller.cc",
+      "sync/glue/extension_model_type_controller.h",
       "sync/glue/extension_setting_data_type_controller.cc",
       "sync/glue/extension_setting_data_type_controller.h",
       "sync/glue/theme_data_type_controller.cc",

chrome/browser/sync/chrome_sync_client.cc

@@ -68,10 +68,13 @@
 #include "components/sync/base/report_unrecoverable_error.h"
 #include "components/sync/driver/async_directory_type_controller.h"
 #include "components/sync/driver/sync_api_component_factory.h"
+#include "components/sync/driver/sync_driver_switches.h"
 #include "components/sync/driver/sync_util.h"
+#include "components/sync/driver/syncable_service_based_model_type_controller.h"
 #include "components/sync/engine/passive_model_worker.h"
 #include "components/sync/engine/sequenced_model_worker.h"
 #include "components/sync/engine/ui_model_worker.h"
+#include "components/sync/model/model_type_store_service.h"
 #include "components/sync/user_events/user_event_service.h"
 #include "components/sync_bookmarks/bookmark_sync_service.h"
 #include "components/sync_preferences/pref_service_syncable.h"
@@ -93,6 +96,7 @@
 #include "chrome/browser/extensions/api/storage/settings_sync_util.h"
 #include "chrome/browser/extensions/extension_sync_service.h"
 #include "chrome/browser/sync/glue/extension_data_type_controller.h"
+#include "chrome/browser/sync/glue/extension_model_type_controller.h"
 #include "chrome/browser/sync/glue/extension_setting_data_type_controller.h"
 #endif  // BUILDFLAG(ENABLE_EXTENSIONS)
 
@@ -124,6 +128,7 @@
 using content::BrowserThread;
 #if BUILDFLAG(ENABLE_EXTENSIONS)
 using browser_sync::ExtensionDataTypeController;
+using browser_sync::ExtensionModelTypeController;
 using browser_sync::ExtensionSettingDataTypeController;
 #endif  // BUILDFLAG(ENABLE_EXTENSIONS)
 using browser_sync::SearchEngineDataTypeController;
@@ -295,16 +300,32 @@ ChromeSyncClient::CreateDataTypeControllers(
   // App sync is enabled by default.  Register unless explicitly
   // disabled.
   if (!disabled_types.Has(syncer::APPS)) {
+    if (base::FeatureList::IsEnabled(switches::kSyncPseudoUSSApps)) {
+      controllers.push_back(std::make_unique<ExtensionModelTypeController>(
+          syncer::APPS, GetModelTypeStoreService()->GetStoreFactory(),
+          base::BindOnce(&ChromeSyncClient::GetSyncableServiceForType,
+                         base::Unretained(this), syncer::APPS),
+          profile_));
+    } else {
       controllers.push_back(std::make_unique<ExtensionDataTypeController>(
           syncer::APPS, error_callback, this, profile_));
     }
+  }
 
   // Extension sync is enabled by default.  Register unless explicitly
   // disabled.
   if (!disabled_types.Has(syncer::EXTENSIONS)) {
+    if (base::FeatureList::IsEnabled(switches::kSyncPseudoUSSExtensions)) {
+      controllers.push_back(std::make_unique<ExtensionModelTypeController>(
+          syncer::EXTENSIONS, GetModelTypeStoreService()->GetStoreFactory(),
+          base::BindOnce(&ChromeSyncClient::GetSyncableServiceForType,
+                         base::Unretained(this), syncer::EXTENSIONS),
+          profile_));
+    } else {
       controllers.push_back(std::make_unique<ExtensionDataTypeController>(
           syncer::EXTENSIONS, error_callback, this, profile_));
     }
+  }
 
   // Extension setting sync is enabled by default.  Register unless explicitly
   // disabled.
@@ -324,9 +345,17 @@ ChromeSyncClient::CreateDataTypeControllers(
 #if !defined(OS_ANDROID)
   // Theme sync is enabled by default.  Register unless explicitly disabled.
   if (!disabled_types.Has(syncer::THEMES)) {
+    if (base::FeatureList::IsEnabled(switches::kSyncPseudoUSSThemes)) {
+      controllers.push_back(std::make_unique<ExtensionModelTypeController>(
+          syncer::THEMES, GetModelTypeStoreService()->GetStoreFactory(),
+          base::BindOnce(&ChromeSyncClient::GetSyncableServiceForType,
+                         base::Unretained(this), syncer::THEMES),
+          profile_));
+    } else {
       controllers.push_back(std::make_unique<ThemeDataTypeController>(
           error_callback, this, profile_));
     }
+  }
 
   // Search Engine sync is enabled by default.  Register unless explicitly
   // disabled.
@@ -338,18 +367,34 @@ ChromeSyncClient::CreateDataTypeControllers(
 #endif  // !defined(OS_ANDROID)
 
 #if BUILDFLAG(ENABLE_APP_LIST)
+  if (base::FeatureList::IsEnabled(switches::kSyncPseudoUSSAppList)) {
+    controllers.push_back(
+        std::make_unique<syncer::SyncableServiceBasedModelTypeController>(
+            syncer::APP_LIST, GetModelTypeStoreService()->GetStoreFactory(),
+            base::BindOnce(&ChromeSyncClient::GetSyncableServiceForType,
+                           base::Unretained(this), syncer::APP_LIST)));
+  } else {
     controllers.push_back(std::make_unique<AsyncDirectoryTypeController>(
         syncer::APP_LIST, error_callback, this, syncer::GROUP_UI,
         base::CreateSingleThreadTaskRunnerWithTraits({BrowserThread::UI})));
+  }
 #endif  // BUILDFLAG(ENABLE_APP_LIST)
 
 #if defined(OS_LINUX) || defined(OS_WIN)
   // Dictionary sync is enabled by default.
   if (!disabled_types.Has(syncer::DICTIONARY)) {
+    if (base::FeatureList::IsEnabled(switches::kSyncPseudoUSSDictionary)) {
+      controllers.push_back(
+          std::make_unique<syncer::SyncableServiceBasedModelTypeController>(
+              syncer::DICTIONARY, GetModelTypeStoreService()->GetStoreFactory(),
+              base::BindOnce(&ChromeSyncClient::GetSyncableServiceForType,
+                             base::Unretained(this), syncer::DICTIONARY)));
+    } else {
       controllers.push_back(std::make_unique<AsyncDirectoryTypeController>(
           syncer::DICTIONARY, error_callback, this, syncer::GROUP_UI,
           base::CreateSingleThreadTaskRunnerWithTraits({BrowserThread::UI})));
     }
+  }
 #endif  // defined(OS_LINUX) || defined(OS_WIN)
 
 #if defined(OS_CHROMEOS)

chrome/browser/sync/glue/extension_model_type_controller.cc

+// 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 "chrome/browser/sync/glue/extension_model_type_controller.h"
+
+#include <utility>
+
+#include "chrome/browser/profiles/profile.h"
+#include "extensions/browser/extension_system.h"
+
+namespace browser_sync {
+
+ExtensionModelTypeController::ExtensionModelTypeController(
+    syncer::ModelType type,
+    syncer::OnceModelTypeStoreFactory store_factory,
+    SyncableServiceProvider syncable_service_provider,
+    Profile* profile)
+    : SyncableServiceBasedModelTypeController(
+          type,
+          std::move(store_factory),
+          std::move(syncable_service_provider)),
+      profile_(profile) {
+  DCHECK(type == syncer::EXTENSIONS || type == syncer::APPS ||
+         type == syncer::THEMES);
+}
+
+ExtensionModelTypeController::~ExtensionModelTypeController() {}
+
+void ExtensionModelTypeController::LoadModels(
+    const syncer::ConfigureContext& configure_context,
+    const ModelLoadCallback& model_load_callback) {
+  DCHECK(CalledOnValidThread());
+  extensions::ExtensionSystem::Get(profile_)->InitForRegularProfile(
+      /*extensions_enabled=*/true);
+  ModelTypeController::LoadModels(configure_context, model_load_callback);
+}
+
+}  // namespace browser_sync

chrome/browser/sync/glue/extension_model_type_controller.h

+// 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 CHROME_BROWSER_SYNC_GLUE_EXTENSION_MODEL_TYPE_CONTROLLER_H_
+#define CHROME_BROWSER_SYNC_GLUE_EXTENSION_MODEL_TYPE_CONTROLLER_H_
+
+#include "base/macros.h"
+#include "components/sync/driver/syncable_service_based_model_type_controller.h"
+
+class Profile;
+
+namespace browser_sync {
+
+// Controller with custom logic to start the extensions machinery when sync is
+// starting. Analogous to ExtensionDataTypeController and
+// ThemeDataTypeController.
+class ExtensionModelTypeController
+    : public syncer::SyncableServiceBasedModelTypeController {
+ public:
+  ExtensionModelTypeController(
+      syncer::ModelType type,
+      syncer::OnceModelTypeStoreFactory store_factory,
+      SyncableServiceProvider syncable_service_provider,
+      Profile* profile);
+  ~ExtensionModelTypeController() override;
+
+  // DataTypeController overrides.
+  void LoadModels(const syncer::ConfigureContext& configure_context,
+                  const ModelLoadCallback& model_load_callback) override;
+
+ private:
+  Profile* const profile_;
+
+  DISALLOW_COPY_AND_ASSIGN(ExtensionModelTypeController);
+};
+
+}  // namespace browser_sync
+
+#endif  // CHROME_BROWSER_SYNC_GLUE_EXTENSION_MODEL_TYPE_CONTROLLER_H_

chrome/browser/sync/test/integration/single_client_apps_sync_test.cc

@@ -3,16 +3,36 @@
 // found in the LICENSE file.
 
 #include "base/macros.h"
+#include "base/test/scoped_feature_list.h"
 #include "chrome/browser/sync/test/integration/apps_helper.h"
 #include "chrome/browser/sync/test/integration/sync_test.h"
 #include "chrome/browser/sync/test/integration/updated_progress_marker_checker.h"
 #include "components/browser_sync/profile_sync_service.h"
+#include "components/sync/driver/sync_driver_switches.h"
+
+namespace {
 
 using apps_helper::AllProfilesHaveSameApps;
 using apps_helper::InstallApp;
 using apps_helper::InstallPlatformApp;
 
-class SingleClientAppsSyncTest : public SyncTest {
+// Class that enables or disables USS based on test parameter. Must be the first
+// base class of the test fixture.
+class UssSwitchToggler : public testing::WithParamInterface<bool> {
+ public:
+  UssSwitchToggler() {
+    if (GetParam()) {
+      override_features_.InitAndEnableFeature(switches::kSyncPseudoUSSApps);
+    } else {
+      override_features_.InitAndDisableFeature(switches::kSyncPseudoUSSApps);
+    }
+  }
+
+ private:
+  base::test::ScopedFeatureList override_features_;
+};
+
+class SingleClientAppsSyncTest : public UssSwitchToggler, public SyncTest {
  public:
   SingleClientAppsSyncTest() : SyncTest(SINGLE_CLIENT) {}
 
@@ -22,12 +42,12 @@ class SingleClientAppsSyncTest : public SyncTest {
   DISALLOW_COPY_AND_ASSIGN(SingleClientAppsSyncTest);
 };
 
-IN_PROC_BROWSER_TEST_F(SingleClientAppsSyncTest, StartWithNoApps) {
+IN_PROC_BROWSER_TEST_P(SingleClientAppsSyncTest, StartWithNoApps) {
   ASSERT_TRUE(SetupSync());
   ASSERT_TRUE(AllProfilesHaveSameApps());
 }
 
-IN_PROC_BROWSER_TEST_F(SingleClientAppsSyncTest, StartWithSomeLegacyApps) {
+IN_PROC_BROWSER_TEST_P(SingleClientAppsSyncTest, StartWithSomeLegacyApps) {
   ASSERT_TRUE(SetupClients());
 
   const int kNumApps = 5;
@@ -40,7 +60,7 @@ IN_PROC_BROWSER_TEST_F(SingleClientAppsSyncTest, StartWithSomeLegacyApps) {
   ASSERT_TRUE(AllProfilesHaveSameApps());
 }
 
-IN_PROC_BROWSER_TEST_F(SingleClientAppsSyncTest, StartWithSomePlatformApps) {
+IN_PROC_BROWSER_TEST_P(SingleClientAppsSyncTest, StartWithSomePlatformApps) {
   ASSERT_TRUE(SetupClients());
 
   const int kNumApps = 5;
@@ -53,7 +73,7 @@ IN_PROC_BROWSER_TEST_F(SingleClientAppsSyncTest, StartWithSomePlatformApps) {
   ASSERT_TRUE(AllProfilesHaveSameApps());
 }
 
-IN_PROC_BROWSER_TEST_F(SingleClientAppsSyncTest, InstallSomeLegacyApps) {
+IN_PROC_BROWSER_TEST_P(SingleClientAppsSyncTest, InstallSomeLegacyApps) {
   ASSERT_TRUE(SetupSync());
 
   const int kNumApps = 5;
@@ -66,7 +86,7 @@ IN_PROC_BROWSER_TEST_F(SingleClientAppsSyncTest, InstallSomeLegacyApps) {
   ASSERT_TRUE(AllProfilesHaveSameApps());
 }
 
-IN_PROC_BROWSER_TEST_F(SingleClientAppsSyncTest, InstallSomePlatformApps) {
+IN_PROC_BROWSER_TEST_P(SingleClientAppsSyncTest, InstallSomePlatformApps) {
   ASSERT_TRUE(SetupSync());
 
   const int kNumApps = 5;
@@ -79,7 +99,7 @@ IN_PROC_BROWSER_TEST_F(SingleClientAppsSyncTest, InstallSomePlatformApps) {
   ASSERT_TRUE(AllProfilesHaveSameApps());
 }
 
-IN_PROC_BROWSER_TEST_F(SingleClientAppsSyncTest, InstallSomeApps) {
+IN_PROC_BROWSER_TEST_P(SingleClientAppsSyncTest, InstallSomeApps) {
   ASSERT_TRUE(SetupSync());
 
   int i = 0;
@@ -99,3 +119,9 @@ IN_PROC_BROWSER_TEST_F(SingleClientAppsSyncTest, InstallSomeApps) {
   ASSERT_TRUE(UpdatedProgressMarkerChecker(GetSyncService(0)).Wait());
   ASSERT_TRUE(AllProfilesHaveSameApps());
 }
+
+INSTANTIATE_TEST_CASE_P(USS,
+                        SingleClientAppsSyncTest,
+                        ::testing::Values(false, true));
+
+}  // namespace

chrome/browser/sync/test/integration/single_client_dictionary_sync_test.cc

@@ -3,12 +3,35 @@
 // found in the LICENSE file.
 
 #include "base/macros.h"
+#include "base/test/scoped_feature_list.h"
 #include "chrome/browser/sync/test/integration/dictionary_helper.h"
 #include "chrome/browser/sync/test/integration/sync_test.h"
 #include "chrome/browser/sync/test/integration/updated_progress_marker_checker.h"
 #include "components/browser_sync/profile_sync_service.h"
+#include "components/sync/driver/sync_driver_switches.h"
 
-class SingleClientDictionarySyncTest : public SyncTest {
+namespace {
+
+// Class that enables or disables USS based on test parameter. Must be the first
+// base class of the test fixture.
+class UssSwitchToggler : public testing::WithParamInterface<bool> {
+ public:
+  UssSwitchToggler() {
+    if (GetParam()) {
+      override_features_.InitAndEnableFeature(
+          switches::kSyncPseudoUSSDictionary);
+    } else {
+      override_features_.InitAndDisableFeature(
+          switches::kSyncPseudoUSSDictionary);
+    }
+  }
+
+ private:
+  base::test::ScopedFeatureList override_features_;
+};
+
+class SingleClientDictionarySyncTest : public UssSwitchToggler,
+                                       public SyncTest {
  public:
   SingleClientDictionarySyncTest() : SyncTest(SINGLE_CLIENT) {}
   ~SingleClientDictionarySyncTest() override {}
@@ -17,7 +40,7 @@ class SingleClientDictionarySyncTest : public SyncTest {
   DISALLOW_COPY_AND_ASSIGN(SingleClientDictionarySyncTest);
 };
 
-IN_PROC_BROWSER_TEST_F(SingleClientDictionarySyncTest, Sanity) {
+IN_PROC_BROWSER_TEST_P(SingleClientDictionarySyncTest, Sanity) {
   ASSERT_TRUE(SetupSync()) << "SetupSync() failed.";
   dictionary_helper::LoadDictionaries();
   ASSERT_TRUE(dictionary_helper::DictionariesMatch());
@@ -31,3 +54,9 @@ IN_PROC_BROWSER_TEST_F(SingleClientDictionarySyncTest, Sanity) {
   ASSERT_TRUE(UpdatedProgressMarkerChecker(GetSyncService(0)).Wait());
   ASSERT_TRUE(dictionary_helper::DictionariesMatch());
 }
+
+INSTANTIATE_TEST_CASE_P(USS,
+                        SingleClientDictionarySyncTest,
+                        ::testing::Values(false, true));
+
+}  // namespace

chrome/browser/sync/test/integration/single_client_extensions_sync_test.cc

@@ -3,20 +3,43 @@
 // found in the LICENSE file.
 
 #include "base/macros.h"
+#include "base/test/scoped_feature_list.h"
 #include "chrome/browser/sync/test/integration/await_match_status_change_checker.h"
 #include "chrome/browser/sync/test/integration/extensions_helper.h"
 #include "chrome/browser/sync/test/integration/sync_test.h"
 #include "chrome/browser/sync/test/integration/updated_progress_marker_checker.h"
 #include "components/browser_sync/profile_sync_service.h"
+#include "components/sync/driver/sync_driver_switches.h"
 #include "components/sync/test/fake_server/fake_server.h"
 
+namespace {
+
 using extensions_helper::AllProfilesHaveSameExtensionsAsVerifier;
 using extensions_helper::DisableExtension;
 using extensions_helper::GetInstalledExtensions;
 using extensions_helper::InstallExtension;
 using extensions_helper::InstallExtensionForAllProfiles;
 
-class SingleClientExtensionsSyncTest : public SyncTest {
+// Class that enables or disables USS based on test parameter. Must be the first
+// base class of the test fixture.
+class UssSwitchToggler : public testing::WithParamInterface<bool> {
+ public:
+  UssSwitchToggler() {
+    if (GetParam()) {
+      override_features_.InitAndEnableFeature(
+          switches::kSyncPseudoUSSExtensions);
+    } else {
+      override_features_.InitAndDisableFeature(
+          switches::kSyncPseudoUSSExtensions);
+    }
+  }
+
+ private:
+  base::test::ScopedFeatureList override_features_;
+};
+
+class SingleClientExtensionsSyncTest : public UssSwitchToggler,
+                                       public SyncTest {
  public:
   SingleClientExtensionsSyncTest() : SyncTest(SINGLE_CLIENT) {}
 
@@ -26,12 +49,12 @@ class SingleClientExtensionsSyncTest : public SyncTest {
   DISALLOW_COPY_AND_ASSIGN(SingleClientExtensionsSyncTest);
 };
 
-IN_PROC_BROWSER_TEST_F(SingleClientExtensionsSyncTest, StartWithNoExtensions) {
+IN_PROC_BROWSER_TEST_P(SingleClientExtensionsSyncTest, StartWithNoExtensions) {
   ASSERT_TRUE(SetupSync());
   ASSERT_TRUE(AllProfilesHaveSameExtensionsAsVerifier());
 }
 
-IN_PROC_BROWSER_TEST_F(SingleClientExtensionsSyncTest,
+IN_PROC_BROWSER_TEST_P(SingleClientExtensionsSyncTest,
                        StartWithSomeExtensions) {
   ASSERT_TRUE(SetupClients());
 
@@ -45,7 +68,7 @@ IN_PROC_BROWSER_TEST_F(SingleClientExtensionsSyncTest,
   ASSERT_TRUE(AllProfilesHaveSameExtensionsAsVerifier());
 }
 
-IN_PROC_BROWSER_TEST_F(SingleClientExtensionsSyncTest, InstallSomeExtensions) {
+IN_PROC_BROWSER_TEST_P(SingleClientExtensionsSyncTest, InstallSomeExtensions) {
   ASSERT_TRUE(SetupSync());
 
   const int kNumExtensions = 5;
@@ -66,7 +89,7 @@ static bool ExtensionCountCheck(Profile* profile, size_t expected_count) {
 
 // Tests the case of an uninstall from the server conflicting with a local
 // modification, which we expect to be resolved in favor of the uninstall.
-IN_PROC_BROWSER_TEST_F(SingleClientExtensionsSyncTest, UninstallWinsConflicts) {
+IN_PROC_BROWSER_TEST_P(SingleClientExtensionsSyncTest, UninstallWinsConflicts) {
   ASSERT_TRUE(SetupClients());
 
   // Start with an extension installed, and setup sync.
@@ -102,3 +125,9 @@ IN_PROC_BROWSER_TEST_F(SingleClientExtensionsSyncTest, UninstallWinsConflicts) {
   EXPECT_TRUE(checker.Wait());
   EXPECT_TRUE(GetInstalledExtensions(GetProfile(0)).empty());
 }
+
+INSTANTIATE_TEST_CASE_P(USS,
+                        SingleClientExtensionsSyncTest,
+                        ::testing::Values(false, true));
+
+}  // namespace

chrome/browser/sync/test/integration/single_client_themes_sync_test.cc

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 #include "base/macros.h"
+#include "base/test/scoped_feature_list.h"
 #include "build/build_config.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/sync/test/integration/sync_integration_test_util.h"
@@ -11,6 +12,7 @@
 #include "chrome/browser/sync/test/integration/updated_progress_marker_checker.h"
 #include "chrome/browser/themes/theme_service_factory.h"
 #include "components/browser_sync/profile_sync_service.h"
+#include "components/sync/driver/sync_driver_switches.h"
 #include "content/public/test/test_utils.h"
 
 using themes_helper::GetCustomTheme;
@@ -23,7 +25,23 @@ using themes_helper::UsingSystemTheme;
 
 namespace {
 
-class SingleClientThemesSyncTest : public SyncTest {
+// Class that enables or disables USS based on test parameter. Must be the first
+// base class of the test fixture.
+class UssSwitchToggler : public testing::WithParamInterface<bool> {
+ public:
+  UssSwitchToggler() {
+    if (GetParam()) {
+      override_features_.InitAndEnableFeature(switches::kSyncPseudoUSSThemes);
+    } else {
+      override_features_.InitAndDisableFeature(switches::kSyncPseudoUSSThemes);
+    }
+  }
+
+ private:
+  base::test::ScopedFeatureList override_features_;
+};
+
+class SingleClientThemesSyncTest : public UssSwitchToggler, public SyncTest {
  public:
   SingleClientThemesSyncTest() : SyncTest(SINGLE_CLIENT) {}
   ~SingleClientThemesSyncTest() override {}
@@ -36,7 +54,7 @@ class SingleClientThemesSyncTest : public SyncTest {
 // start with SetupClients(), change the theme state, then call
 // SetupSync()).
 
-IN_PROC_BROWSER_TEST_F(SingleClientThemesSyncTest, CustomTheme) {
+IN_PROC_BROWSER_TEST_P(SingleClientThemesSyncTest, CustomTheme) {
   ASSERT_TRUE(SetupSync()) << "SetupSync() failed.";
 
   EXPECT_FALSE(UsingCustomTheme(GetProfile(0)));
@@ -55,9 +73,9 @@ IN_PROC_BROWSER_TEST_F(SingleClientThemesSyncTest, CustomTheme) {
 
 // TODO(sync): Fails on Chrome OS. See http://crbug.com/84575.
 #if defined(OS_CHROMEOS)
-IN_PROC_BROWSER_TEST_F(SingleClientThemesSyncTest, DISABLED_NativeTheme) {
+IN_PROC_BROWSER_TEST_P(SingleClientThemesSyncTest, DISABLED_NativeTheme) {
 #else
-IN_PROC_BROWSER_TEST_F(SingleClientThemesSyncTest, NativeTheme) {
+IN_PROC_BROWSER_TEST_P(SingleClientThemesSyncTest, NativeTheme) {
 #endif  // OS_CHROMEOS
   ASSERT_TRUE(SetupSync()) << "SetupSync() failed.";
 
@@ -79,7 +97,7 @@ IN_PROC_BROWSER_TEST_F(SingleClientThemesSyncTest, NativeTheme) {
   EXPECT_TRUE(UsingSystemTheme(verifier()));
 }
 
-IN_PROC_BROWSER_TEST_F(SingleClientThemesSyncTest, DefaultTheme) {
+IN_PROC_BROWSER_TEST_P(SingleClientThemesSyncTest, DefaultTheme) {
   ASSERT_TRUE(SetupSync()) << "SetupSync() failed.";
 
   SetCustomTheme(GetProfile(0));
@@ -100,4 +118,8 @@ IN_PROC_BROWSER_TEST_F(SingleClientThemesSyncTest, DefaultTheme) {
   EXPECT_TRUE(UsingDefaultTheme(verifier()));
 }
 
+INSTANTIATE_TEST_CASE_P(USS,
+                        SingleClientThemesSyncTest,
+                        ::testing::Values(false, true));
+
 }  // namespace

chrome/browser/sync/test/integration/two_client_apps_sync_test.cc

@@ -6,6 +6,7 @@
 
 #include "base/macros.h"
 #include "base/strings/utf_string_conversions.h"
+#include "base/test/scoped_feature_list.h"
 #include "build/build_config.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/extensions/bookmark_app_helper.h"
@@ -22,6 +23,7 @@
 #include "chrome/browser/web_applications/extensions/bookmark_app_util.h"
 #include "chrome/common/extensions/manifest_handlers/app_launch_info.h"
 #include "chrome/common/extensions/manifest_handlers/app_theme_color_info.h"
+#include "components/sync/driver/sync_driver_switches.h"
 #include "components/sync/model/string_ordinal.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/test/test_utils.h"
@@ -47,6 +49,22 @@ using apps_helper::UninstallApp;
 
 namespace {
 
+// Class that enables or disables USS based on test parameter. Must be the first
+// base class of the test fixture.
+class UssSwitchToggler : public testing::WithParamInterface<bool> {
+ public:
+  UssSwitchToggler() {
+    if (GetParam()) {
+      override_features_.InitAndEnableFeature(switches::kSyncPseudoUSSApps);
+    } else {
+      override_features_.InitAndDisableFeature(switches::kSyncPseudoUSSApps);
+    }
+  }
+
+ private:
+  base::test::ScopedFeatureList override_features_;
+};
+
 extensions::ExtensionRegistry* GetExtensionRegistry(Profile* profile) {
   return extensions::ExtensionRegistry::Get(profile);
 }
@@ -57,7 +75,7 @@ extensions::ExtensionService* GetExtensionService(Profile* profile) {
 
 }  // namespace
 
-class TwoClientAppsSyncTest : public SyncTest {
+class TwoClientAppsSyncTest : public UssSwitchToggler, public SyncTest {
  public:
   TwoClientAppsSyncTest() : SyncTest(TWO_CLIENT) {
     DisableVerifier();
@@ -71,12 +89,12 @@ class TwoClientAppsSyncTest : public SyncTest {
   DISALLOW_COPY_AND_ASSIGN(TwoClientAppsSyncTest);
 };
 
-IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest, E2E_ENABLED(StartWithNoApps)) {
+IN_PROC_BROWSER_TEST_P(TwoClientAppsSyncTest, E2E_ENABLED(StartWithNoApps)) {
   ASSERT_TRUE(SetupSync());
   ASSERT_TRUE(AppsMatchChecker().Wait());
 }
 
-IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest, E2E_ENABLED(StartWithSameApps)) {
+IN_PROC_BROWSER_TEST_P(TwoClientAppsSyncTest, E2E_ENABLED(StartWithSameApps)) {
   ASSERT_TRUE(SetupClients());
 
   const int kNumApps = 5;
@@ -98,7 +116,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest, E2E_ENABLED(StartWithSameApps)) {
 #else
 #define MAYBE_StartWithDifferentApps StartWithDifferentApps
 #endif
-IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest, MAYBE_StartWithDifferentApps) {
+IN_PROC_BROWSER_TEST_P(TwoClientAppsSyncTest, MAYBE_StartWithDifferentApps) {
   ASSERT_TRUE(SetupClients());
 
   int i = 0;
@@ -131,7 +149,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest, MAYBE_StartWithDifferentApps) {
 // Install some apps on both clients, then sync.  Then install some apps on only
 // one client, some on only the other, and then sync again.  Both clients should
 // end up with all apps, and the app and page ordinals should be identical.
-IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest,
+IN_PROC_BROWSER_TEST_P(TwoClientAppsSyncTest,
                        E2E_ENABLED(InstallDifferentApps)) {
   ASSERT_TRUE(SetupClients());
 
@@ -158,7 +176,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest,
   ASSERT_TRUE(AppsMatchChecker().Wait());
 }
 
-IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest, E2E_ENABLED(Add)) {
+IN_PROC_BROWSER_TEST_P(TwoClientAppsSyncTest, E2E_ENABLED(Add)) {
   ASSERT_TRUE(SetupSync());
   ASSERT_TRUE(AppsMatchChecker().Wait());
 
@@ -167,7 +185,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest, E2E_ENABLED(Add)) {
   ASSERT_TRUE(AppsMatchChecker().Wait());
 }
 
-IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest, E2E_ENABLED(Uninstall)) {
+IN_PROC_BROWSER_TEST_P(TwoClientAppsSyncTest, E2E_ENABLED(Uninstall)) {
   ASSERT_TRUE(SetupSync());
   ASSERT_TRUE(AppsMatchChecker().Wait());
 
@@ -182,7 +200,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest, E2E_ENABLED(Uninstall)) {
 // client and sync again. Now install a new app on the first client and sync.
 // Both client should only have the second app, with identical app and page
 // ordinals.
-IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest,
+IN_PROC_BROWSER_TEST_P(TwoClientAppsSyncTest,
                        E2E_ENABLED(UninstallThenInstall)) {
   ASSERT_TRUE(SetupSync());
   ASSERT_TRUE(AppsMatchChecker().Wait());
@@ -197,7 +215,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest,
   ASSERT_TRUE(AppsMatchChecker().Wait());
 }
 
-IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest, E2E_ENABLED(Merge)) {
+IN_PROC_BROWSER_TEST_P(TwoClientAppsSyncTest, E2E_ENABLED(Merge)) {
   ASSERT_TRUE(SetupSync());
   ASSERT_TRUE(AppsMatchChecker().Wait());
 
@@ -215,7 +233,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest, E2E_ENABLED(Merge)) {
   ASSERT_TRUE(AppsMatchChecker().Wait());
 }
 
-IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest,
+IN_PROC_BROWSER_TEST_P(TwoClientAppsSyncTest,
                        E2E_ENABLED(UpdateEnableDisableApp)) {
   ASSERT_TRUE(SetupSync());
   ASSERT_TRUE(AppsMatchChecker().Wait());
@@ -230,7 +248,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest,
   ASSERT_TRUE(AppsMatchChecker().Wait());
 }
 
-IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest,
+IN_PROC_BROWSER_TEST_P(TwoClientAppsSyncTest,
                        E2E_ENABLED(UpdateIncognitoEnableDisable)) {
   ASSERT_TRUE(SetupSync());
   ASSERT_TRUE(AppsMatchChecker().Wait());
@@ -248,7 +266,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest,
 // Install the same app on both clients, then sync. Change the page ordinal on
 // one client and sync. Both clients should have the updated page ordinal for
 // the app.
-IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest, E2E_ENABLED(UpdatePageOrdinal)) {
+IN_PROC_BROWSER_TEST_P(TwoClientAppsSyncTest, E2E_ENABLED(UpdatePageOrdinal)) {
   ASSERT_TRUE(SetupSync());
   ASSERT_TRUE(AppsMatchChecker().Wait());
 
@@ -265,7 +283,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest, E2E_ENABLED(UpdatePageOrdinal)) {
 // Install the same app on both clients, then sync. Change the app launch
 // ordinal on one client and sync. Both clients should have the updated app
 // launch ordinal for the app.
-IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest,
+IN_PROC_BROWSER_TEST_P(TwoClientAppsSyncTest,
                        E2E_ENABLED(UpdateAppLaunchOrdinal)) {
   ASSERT_TRUE(SetupSync());
   ASSERT_TRUE(AppsMatchChecker().Wait());
@@ -284,7 +302,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest,
 // Adjust the CWS location within a page on the first client and sync. Adjust
 // which page the CWS appears on and sync. Both clients should have the same
 // page and app launch ordinal values for the CWS.
-IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest, E2E_ENABLED(UpdateCWSOrdinals)) {
+IN_PROC_BROWSER_TEST_P(TwoClientAppsSyncTest, E2E_ENABLED(UpdateCWSOrdinals)) {
   ASSERT_TRUE(SetupSync());
   ASSERT_TRUE(AppsMatchChecker().Wait());
 
@@ -313,7 +331,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest, E2E_ENABLED(UpdateCWSOrdinals)) {
 
 // Adjust the launch type on the first client and sync. Both clients should
 // have the same launch type values for the CWS.
-IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest, E2E_ENABLED(UpdateLaunchType)) {
+IN_PROC_BROWSER_TEST_P(TwoClientAppsSyncTest, E2E_ENABLED(UpdateLaunchType)) {
   ASSERT_TRUE(SetupSync());
   ASSERT_TRUE(AppsMatchChecker().Wait());
 
@@ -339,7 +357,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest, E2E_ENABLED(UpdateLaunchType)) {
       extensions::LAUNCH_TYPE_REGULAR);
 }
 
-IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest, UnexpectedLaunchType) {
+IN_PROC_BROWSER_TEST_P(TwoClientAppsSyncTest, UnexpectedLaunchType) {
   ASSERT_TRUE(SetupSync());
   ASSERT_TRUE(AllProfilesHaveSameApps());
 
@@ -378,7 +396,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest, UnexpectedLaunchType) {
   ASSERT_TRUE(AppsMatchChecker().Wait());
 }
 
-IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest, BookmarkAppBasic) {
+IN_PROC_BROWSER_TEST_P(TwoClientAppsSyncTest, BookmarkAppBasic) {
   ASSERT_TRUE(SetupSync());
   ASSERT_TRUE(AllProfilesHaveSameApps());
 
@@ -411,7 +429,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest, BookmarkAppBasic) {
   }
 }
 
-IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest, BookmarkAppMinimal) {
+IN_PROC_BROWSER_TEST_P(TwoClientAppsSyncTest, BookmarkAppMinimal) {
   ASSERT_TRUE(SetupSync());
   ASSERT_TRUE(AllProfilesHaveSameApps());
 
@@ -453,7 +471,7 @@ const extensions::Extension* GetAppByLaunchURL(const GURL& url,
   return nullptr;
 }
 
-IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest, BookmarkAppThemeColor) {
+IN_PROC_BROWSER_TEST_P(TwoClientAppsSyncTest, BookmarkAppThemeColor) {
   ASSERT_TRUE(SetupSync());
   ASSERT_TRUE(AllProfilesHaveSameApps());
 
@@ -489,7 +507,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest, BookmarkAppThemeColor) {
   EXPECT_EQ(SK_ColorBLUE, theme_color.value());
 }
 
-IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest, IsLocallyInstalled) {
+IN_PROC_BROWSER_TEST_P(TwoClientAppsSyncTest, IsLocallyInstalled) {
   ASSERT_TRUE(SetupSync());
   ASSERT_TRUE(AllProfilesHaveSameApps());
 
@@ -541,3 +559,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientAppsSyncTest, IsLocallyInstalled) {
 // TODO(akalin): Add tests exercising:
 //   - Offline installation/uninstallation behavior
 //   - App-specific properties
+
+INSTANTIATE_TEST_CASE_P(USS,
+                        TwoClientAppsSyncTest,
+                        ::testing::Values(false, true));

chrome/browser/sync/test/integration/two_client_dictionary_sync_test.cc

@@ -4,6 +4,7 @@
 
 #include "base/macros.h"
 #include "base/strings/string_number_conversions.h"
+#include "base/test/scoped_feature_list.h"
 #include "chrome/browser/sync/test/integration/dictionary_helper.h"
 #include "chrome/browser/sync/test/integration/profile_sync_service_harness.h"
 #include "chrome/browser/sync/test/integration/sync_integration_test_util.h"
@@ -11,10 +12,31 @@
 #include "chrome/browser/sync/test/integration/updated_progress_marker_checker.h"
 #include "components/spellcheck/common/spellcheck_common.h"
 #include "components/sync/base/model_type.h"
+#include "components/sync/driver/sync_driver_switches.h"
+
+namespace {
 
 using spellcheck::kMaxSyncableDictionaryWords;
 
-class TwoClientDictionarySyncTest : public SyncTest {
+// Class that enables or disables USS based on test parameter. Must be the first
+// base class of the test fixture.
+class UssSwitchToggler : public testing::WithParamInterface<bool> {
+ public:
+  UssSwitchToggler() {
+    if (GetParam()) {
+      override_features_.InitAndEnableFeature(
+          switches::kSyncPseudoUSSDictionary);
+    } else {
+      override_features_.InitAndDisableFeature(
+          switches::kSyncPseudoUSSDictionary);
+    }
+  }
+
+ private:
+  base::test::ScopedFeatureList override_features_;
+};
+
+class TwoClientDictionarySyncTest : public UssSwitchToggler, public SyncTest {
  public:
   TwoClientDictionarySyncTest() : SyncTest(TWO_CLIENT) {}
   ~TwoClientDictionarySyncTest() override {}
@@ -25,7 +47,7 @@ class TwoClientDictionarySyncTest : public SyncTest {
   DISALLOW_COPY_AND_ASSIGN(TwoClientDictionarySyncTest);
 };
 
-IN_PROC_BROWSER_TEST_F(TwoClientDictionarySyncTest, E2E_ENABLED(Sanity)) {
+IN_PROC_BROWSER_TEST_P(TwoClientDictionarySyncTest, E2E_ENABLED(Sanity)) {
   ASSERT_TRUE(SetupSync()) << "SetupSync() failed.";
   dictionary_helper::LoadDictionaries();
   ASSERT_TRUE(DictionaryMatchChecker().Wait());
@@ -54,7 +76,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientDictionarySyncTest, E2E_ENABLED(Sanity)) {
   ASSERT_EQ(words.size(), dictionary_helper::GetDictionarySize(0));
 }
 
-IN_PROC_BROWSER_TEST_F(TwoClientDictionarySyncTest,
+IN_PROC_BROWSER_TEST_P(TwoClientDictionarySyncTest,
                        E2E_ENABLED(SimultaneousAdd)) {
   ASSERT_TRUE(SetupSync()) << "SetupSync() failed.";
   dictionary_helper::LoadDictionaries();
@@ -66,7 +88,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientDictionarySyncTest,
   ASSERT_EQ(1UL, dictionary_helper::GetDictionarySize(0));
 }
 
-IN_PROC_BROWSER_TEST_F(TwoClientDictionarySyncTest,
+IN_PROC_BROWSER_TEST_P(TwoClientDictionarySyncTest,
                        E2E_ENABLED(SimultaneousRemove)) {
   ASSERT_TRUE(SetupSync()) << "SetupSync() failed.";
   dictionary_helper::LoadDictionaries();
@@ -83,7 +105,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientDictionarySyncTest,
   ASSERT_EQ(0UL, dictionary_helper::GetDictionarySize(0));
 }
 
-IN_PROC_BROWSER_TEST_F(TwoClientDictionarySyncTest,
+IN_PROC_BROWSER_TEST_P(TwoClientDictionarySyncTest,
                        E2E_ENABLED(AddDifferentToEach)) {
   ASSERT_TRUE(SetupSync()) << "SetupSync() failed.";
   dictionary_helper::LoadDictionaries();
@@ -97,7 +119,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientDictionarySyncTest,
             static_cast<int>(dictionary_helper::GetDictionarySize(0)));
 }
 
-IN_PROC_BROWSER_TEST_F(TwoClientDictionarySyncTest,
+IN_PROC_BROWSER_TEST_P(TwoClientDictionarySyncTest,
                        E2E_ENABLED(RemoveOnAAddOnB)) {
   ASSERT_TRUE(SetupSync()) << "SetupSync() failed.";
   dictionary_helper::LoadDictionaries();
@@ -118,7 +140,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientDictionarySyncTest,
 
 // Tests the case where a client has more words added than the
 // kMaxSyncableDictionaryWords limit.
-IN_PROC_BROWSER_TEST_F(TwoClientDictionarySyncTest, Limit) {
+IN_PROC_BROWSER_TEST_P(TwoClientDictionarySyncTest, Limit) {
   ASSERT_TRUE(SetupSync()) << "SetupSync() failed.";
   dictionary_helper::LoadDictionaries();
   ASSERT_TRUE(DictionaryMatchChecker().Wait());
@@ -162,3 +184,9 @@ IN_PROC_BROWSER_TEST_F(TwoClientDictionarySyncTest, Limit) {
   ASSERT_TRUE(
       NumDictionaryEntriesChecker(0, kMaxSyncableDictionaryWords).Wait());
 }
+
+INSTANTIATE_TEST_CASE_P(USS,
+                        TwoClientDictionarySyncTest,
+                        ::testing::Values(false, true));
+
+}  // namespace

chrome/browser/sync/test/integration/two_client_extensions_sync_test.cc

@@ -3,11 +3,15 @@
 // found in the LICENSE file.
 
 #include "base/macros.h"
+#include "base/test/scoped_feature_list.h"
 #include "build/build_config.h"
 #include "chrome/browser/sync/test/integration/extensions_helper.h"
 #include "chrome/browser/sync/test/integration/profile_sync_service_harness.h"
 #include "chrome/browser/sync/test/integration/sync_integration_test_util.h"
 #include "chrome/browser/sync/test/integration/sync_test.h"
+#include "components/sync/driver/sync_driver_switches.h"
+
+namespace {
 
 using extensions_helper::AllProfilesHaveSameExtensions;
 using extensions_helper::DisableExtension;
@@ -19,7 +23,25 @@ using extensions_helper::IncognitoEnableExtension;
 using extensions_helper::InstallExtension;
 using extensions_helper::UninstallExtension;
 
-class TwoClientExtensionsSyncTest : public SyncTest {
+// Class that enables or disables USS based on test parameter. Must be the first
+// base class of the test fixture.
+class UssSwitchToggler : public testing::WithParamInterface<bool> {
+ public:
+  UssSwitchToggler() {
+    if (GetParam()) {
+      override_features_.InitAndEnableFeature(
+          switches::kSyncPseudoUSSExtensions);
+    } else {
+      override_features_.InitAndDisableFeature(
+          switches::kSyncPseudoUSSExtensions);
+    }
+  }
+
+ private:
+  base::test::ScopedFeatureList override_features_;
+};
+
+class TwoClientExtensionsSyncTest : public UssSwitchToggler, public SyncTest {
  public:
   TwoClientExtensionsSyncTest() : SyncTest(TWO_CLIENT) { DisableVerifier(); }
 
@@ -29,7 +51,7 @@ class TwoClientExtensionsSyncTest : public SyncTest {
   DISALLOW_COPY_AND_ASSIGN(TwoClientExtensionsSyncTest);
 };
 
-IN_PROC_BROWSER_TEST_F(TwoClientExtensionsSyncTest,
+IN_PROC_BROWSER_TEST_P(TwoClientExtensionsSyncTest,
                        E2E_ENABLED(StartWithNoExtensions)) {
   ASSERT_TRUE(SetupSync());
   ASSERT_TRUE(ExtensionsMatchChecker().Wait());
@@ -48,7 +70,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientExtensionsSyncTest,
 #else
 #define MAYBE_StartWithSameExtensions StartWithSameExtensions
 #endif
-IN_PROC_BROWSER_TEST_F(TwoClientExtensionsSyncTest,
+IN_PROC_BROWSER_TEST_P(TwoClientExtensionsSyncTest,
                        E2E_ENABLED(MAYBE_StartWithSameExtensions)) {
   ASSERT_TRUE(SetupClients());
 
@@ -70,7 +92,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientExtensionsSyncTest,
 #else
 #define MAYBE_StartWithDifferentExtensions StartWithDifferentExtensions
 #endif
-IN_PROC_BROWSER_TEST_F(TwoClientExtensionsSyncTest,
+IN_PROC_BROWSER_TEST_P(TwoClientExtensionsSyncTest,
                        MAYBE_E2E(MAYBE_StartWithDifferentExtensions)) {
   ASSERT_TRUE(SetupClients());
 
@@ -99,7 +121,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientExtensionsSyncTest,
       static_cast<int>(GetInstalledExtensions(GetProfile(0)).size()));
 }
 
-IN_PROC_BROWSER_TEST_F(TwoClientExtensionsSyncTest,
+IN_PROC_BROWSER_TEST_P(TwoClientExtensionsSyncTest,
                        E2E_ENABLED(InstallDifferentExtensions)) {
   ASSERT_TRUE(SetupClients());
 
@@ -130,7 +152,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientExtensionsSyncTest,
       static_cast<int>(GetInstalledExtensions(GetProfile(0)).size()));
 }
 
-IN_PROC_BROWSER_TEST_F(TwoClientExtensionsSyncTest, MAYBE_E2E(Add)) {
+IN_PROC_BROWSER_TEST_P(TwoClientExtensionsSyncTest, MAYBE_E2E(Add)) {
   ASSERT_TRUE(SetupSync());
   ASSERT_TRUE(AllProfilesHaveSameExtensions());
 
@@ -140,7 +162,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientExtensionsSyncTest, MAYBE_E2E(Add)) {
   EXPECT_EQ(1u, GetInstalledExtensions(GetProfile(0)).size());
 }
 
-IN_PROC_BROWSER_TEST_F(TwoClientExtensionsSyncTest, MAYBE_E2E(Uninstall)) {
+IN_PROC_BROWSER_TEST_P(TwoClientExtensionsSyncTest, MAYBE_E2E(Uninstall)) {
   ASSERT_TRUE(SetupSync());
   ASSERT_TRUE(AllProfilesHaveSameExtensions());
 
@@ -152,7 +174,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientExtensionsSyncTest, MAYBE_E2E(Uninstall)) {
   EXPECT_TRUE(GetInstalledExtensions(GetProfile(0)).empty());
 }
 
-IN_PROC_BROWSER_TEST_F(TwoClientExtensionsSyncTest,
+IN_PROC_BROWSER_TEST_P(TwoClientExtensionsSyncTest,
                        MAYBE_E2E(UpdateEnableDisableExtension)) {
   ASSERT_TRUE(SetupSync());
   ASSERT_TRUE(AllProfilesHaveSameExtensions());
@@ -171,7 +193,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientExtensionsSyncTest,
   ASSERT_TRUE(ExtensionsMatchChecker().Wait());
 }
 
-IN_PROC_BROWSER_TEST_F(TwoClientExtensionsSyncTest,
+IN_PROC_BROWSER_TEST_P(TwoClientExtensionsSyncTest,
                        E2E_ENABLED(UpdateIncognitoEnableDisable)) {
   ASSERT_TRUE(SetupSync());
   ASSERT_TRUE(AllProfilesHaveSameExtensions());
@@ -192,7 +214,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientExtensionsSyncTest,
 
 // Regression test for bug 104399: ensure that an extension installed prior to
 // setting up sync, when uninstalled, is also uninstalled from sync.
-IN_PROC_BROWSER_TEST_F(TwoClientExtensionsSyncTest,
+IN_PROC_BROWSER_TEST_P(TwoClientExtensionsSyncTest,
                        E2E_ENABLED(UninstallPreinstalledExtensions)) {
   ASSERT_TRUE(SetupClients());
   ASSERT_TRUE(AllProfilesHaveSameExtensions());
@@ -212,3 +234,9 @@ IN_PROC_BROWSER_TEST_F(TwoClientExtensionsSyncTest,
 
 // TODO(akalin): Add tests exercising:
 //   - Offline installation/uninstallation behavior
+
+INSTANTIATE_TEST_CASE_P(USS,
+                        TwoClientExtensionsSyncTest,
+                        ::testing::Values(false, true));
+
+}  // namespace

chrome/browser/sync/test/integration/two_client_themes_sync_test.cc

@@ -3,10 +3,14 @@
 // found in the LICENSE file.
 
 #include "base/macros.h"
+#include "base/test/scoped_feature_list.h"
 #include "chrome/browser/sync/test/integration/profile_sync_service_harness.h"
 #include "chrome/browser/sync/test/integration/sync_integration_test_util.h"
 #include "chrome/browser/sync/test/integration/sync_test.h"
 #include "chrome/browser/sync/test/integration/themes_helper.h"
+#include "components/sync/driver/sync_driver_switches.h"
+
+namespace {
 
 using themes_helper::GetCustomTheme;
 using themes_helper::GetThemeID;
@@ -17,7 +21,23 @@ using themes_helper::UsingCustomTheme;
 using themes_helper::UsingDefaultTheme;
 using themes_helper::UsingSystemTheme;
 
-class TwoClientThemesSyncTest : public SyncTest {
+// Class that enables or disables USS based on test parameter. Must be the first
+// base class of the test fixture.
+class UssSwitchToggler : public testing::WithParamInterface<bool> {
+ public:
+  UssSwitchToggler() {
+    if (GetParam()) {
+      override_features_.InitAndEnableFeature(switches::kSyncPseudoUSSThemes);
+    } else {
+      override_features_.InitAndDisableFeature(switches::kSyncPseudoUSSThemes);
+    }
+  }
+
+ private:
+  base::test::ScopedFeatureList override_features_;
+};
+
+class TwoClientThemesSyncTest : public UssSwitchToggler, public SyncTest {
  public:
   TwoClientThemesSyncTest() : SyncTest(TWO_CLIENT) {}
   ~TwoClientThemesSyncTest() override {}
@@ -31,7 +51,7 @@ class TwoClientThemesSyncTest : public SyncTest {
 // Starts with default themes, then sets up sync and uses it to set all
 // profiles to use a custom theme.  Does not actually install any themes, but
 // instead verifies the custom theme is pending for install.
-IN_PROC_BROWSER_TEST_F(TwoClientThemesSyncTest,
+IN_PROC_BROWSER_TEST_P(TwoClientThemesSyncTest,
                        E2E_ENABLED(DefaultThenSyncCustom)) {
   ASSERT_TRUE(SetupSync());
 
@@ -53,7 +73,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientThemesSyncTest,
 
 // Starts with custom themes, then sets up sync and uses it to set all profiles
 // to the system theme.
-IN_PROC_BROWSER_TEST_F(TwoClientThemesSyncTest,
+IN_PROC_BROWSER_TEST_P(TwoClientThemesSyncTest,
                        E2E_ENABLED(CustomThenSyncNative)) {
   ASSERT_TRUE(SetupClients());
 
@@ -73,7 +93,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientThemesSyncTest,
 
 // Starts with custom themes, then sets up sync and uses it to set all profiles
 // to the default theme.
-IN_PROC_BROWSER_TEST_F(TwoClientThemesSyncTest,
+IN_PROC_BROWSER_TEST_P(TwoClientThemesSyncTest,
                        E2E_ENABLED(CustomThenSyncDefault)) {
   ASSERT_TRUE(SetupClients());
 
@@ -94,7 +114,7 @@ IN_PROC_BROWSER_TEST_F(TwoClientThemesSyncTest,
 //
 // Most other tests have significant coverage of model association.  This test
 // is intended to test steady-state scenarios.
-IN_PROC_BROWSER_TEST_F(TwoClientThemesSyncTest, E2E_ENABLED(CycleOptions)) {
+IN_PROC_BROWSER_TEST_P(TwoClientThemesSyncTest, E2E_ENABLED(CycleOptions)) {
   ASSERT_TRUE(SetupSync()) << "SetupSync() failed.";
 
   SetCustomTheme(GetProfile(0));
@@ -120,3 +140,9 @@ IN_PROC_BROWSER_TEST_F(TwoClientThemesSyncTest, E2E_ENABLED(CycleOptions)) {
       ThemePendingInstallChecker(GetProfile(1), GetCustomTheme(1)).Wait());
   EXPECT_EQ(GetCustomTheme(1), GetThemeID(GetProfile(0)));
 }
+
+INSTANTIATE_TEST_CASE_P(USS,
+                        TwoClientThemesSyncTest,
+                        ::testing::Values(false, true));
+
+}  // namespace

components/browser_sync/profile_sync_components_factory_impl.cc

@@ -35,7 +35,9 @@
 #include "components/sync/driver/proxy_data_type_controller.h"
 #include "components/sync/driver/sync_client.h"
 #include "components/sync/driver/sync_driver_switches.h"
+#include "components/sync/driver/syncable_service_based_model_type_controller.h"
 #include "components/sync/engine/sync_engine.h"
+#include "components/sync/model/model_type_store_service.h"
 #include "components/sync/model_impl/forwarding_model_type_controller_delegate.h"
 #include "components/sync/model_impl/proxy_model_type_controller_delegate.h"
 #include "components/sync_bookmarks/bookmark_change_processor.h"
@@ -59,6 +61,7 @@ using syncer::DataTypeManagerImpl;
 using syncer::DataTypeManagerObserver;
 using syncer::ModelTypeController;
 using syncer::ProxyDataTypeController;
+using syncer::SyncableServiceBasedModelTypeController;
 
 namespace browser_sync {
 
@@ -266,7 +269,22 @@ ProfileSyncComponentsFactoryImpl::CreateCommonDataTypeControllers(
     // Favicon sync is enabled by default. Register unless explicitly disabled.
     if (!disabled_types.Has(syncer::FAVICON_IMAGES) &&
         !disabled_types.Has(syncer::FAVICON_TRACKING)) {
-      // crbug/384552. We disable error uploading for this data types for now.
+      if (base::FeatureList::IsEnabled(switches::kSyncPseudoUSSFavicons)) {
+        controllers.push_back(
+            std::make_unique<SyncableServiceBasedModelTypeController>(
+                syncer::FAVICON_IMAGES,
+                sync_client_->GetModelTypeStoreService()->GetStoreFactory(),
+                base::BindOnce(&syncer::SyncClient::GetSyncableServiceForType,
+                               base::Unretained(sync_client_),
+                               syncer::FAVICON_IMAGES)));
+        controllers.push_back(
+            std::make_unique<SyncableServiceBasedModelTypeController>(
+                syncer::FAVICON_TRACKING,
+                sync_client_->GetModelTypeStoreService()->GetStoreFactory(),
+                base::BindOnce(&syncer::SyncClient::GetSyncableServiceForType,
+                               base::Unretained(sync_client_),
+                               syncer::FAVICON_TRACKING)));
+      } else {
         controllers.push_back(std::make_unique<AsyncDirectoryTypeController>(
             syncer::FAVICON_IMAGES, base::RepeatingClosure(), sync_client_,
             syncer::GROUP_UI, ui_thread_));
@@ -275,6 +293,7 @@ ProfileSyncComponentsFactoryImpl::CreateCommonDataTypeControllers(
             syncer::GROUP_UI, ui_thread_));
       }
     }
+  }
 
   // Password sync is enabled by default.  Register unless explicitly
   // disabled.
@@ -285,21 +304,41 @@ ProfileSyncComponentsFactoryImpl::CreateCommonDataTypeControllers(
   }
 
   if (!disabled_types.Has(syncer::PREFERENCES)) {
-    if (!override_prefs_controller_to_uss_for_test_) {
+    if (override_prefs_controller_to_uss_for_test_) {
+      controllers.push_back(CreateModelTypeControllerForModelRunningOnUIThread(
+          syncer::PREFERENCES));
+    } else if (base::FeatureList::IsEnabled(
+                   switches::kSyncPseudoUSSPreferences)) {
+      controllers.push_back(
+          std::make_unique<SyncableServiceBasedModelTypeController>(
+              syncer::PREFERENCES,
+              sync_client_->GetModelTypeStoreService()->GetStoreFactory(),
+              base::BindOnce(&syncer::SyncClient::GetSyncableServiceForType,
+                             base::Unretained(sync_client_),
+                             syncer::PREFERENCES)));
+    } else {
       controllers.push_back(std::make_unique<AsyncDirectoryTypeController>(
           syncer::PREFERENCES, error_callback, sync_client_, syncer::GROUP_UI,
           ui_thread_));
-    } else {
-      controllers.push_back(CreateModelTypeControllerForModelRunningOnUIThread(
-          syncer::PREFERENCES));
     }
   }
 
   if (!disabled_types.Has(syncer::PRIORITY_PREFERENCES)) {
+    if (base::FeatureList::IsEnabled(
+            switches::kSyncPseudoUSSPriorityPreferences)) {
+      controllers.push_back(
+          std::make_unique<SyncableServiceBasedModelTypeController>(
+              syncer::PRIORITY_PREFERENCES,
+              sync_client_->GetModelTypeStoreService()->GetStoreFactory(),
+              base::BindOnce(&syncer::SyncClient::GetSyncableServiceForType,
+                             base::Unretained(sync_client_),
+                             syncer::PRIORITY_PREFERENCES)));
+    } else {
       controllers.push_back(std::make_unique<AsyncDirectoryTypeController>(
           syncer::PRIORITY_PREFERENCES, error_callback, sync_client_,
           syncer::GROUP_UI, ui_thread_));
     }
+  }
 
 #if defined(OS_CHROMEOS)
   if (!disabled_types.Has(syncer::PRINTERS)) {

components/browser_sync/profile_sync_service.h

@@ -677,9 +677,6 @@ class ProfileSyncService : public syncer::SyncService,
   // is decremented back to zero, Sync setup is marked no longer in progress.
   int outstanding_setup_in_progress_handles_ = 0;
 
-  // List of available data type controllers.
-  syncer::DataTypeController::TypeMap data_type_controllers_;
-
   // Whether the SyncEngine has been initialized.
   bool engine_initialized_;
 
@@ -737,6 +734,9 @@ class ProfileSyncService : public syncer::SyncService,
 
   std::unique_ptr<syncer::DeviceInfoSyncBridge> device_info_sync_bridge_;
 
+  // List of available data type controllers.
+  syncer::DataTypeController::TypeMap data_type_controllers_;
+
   std::unique_ptr<syncer::NetworkResources> network_resources_;
 
   const StartBehavior start_behavior_;

components/sync/BUILD.gn

@@ -157,6 +157,8 @@ jumbo_static_library("sync") {
     "driver/sync_type_preference_provider.h",
     "driver/sync_util.cc",
     "driver/sync_util.h",
+    "driver/syncable_service_based_model_type_controller.cc",
+    "driver/syncable_service_based_model_type_controller.h",
     "driver/user_selectable_sync_type.h",
     "engine/commit_queue.cc",
     "engine/commit_queue.h",

components/sync/driver/sync_driver_switches.cc

@@ -46,6 +46,25 @@ const base::Feature kSyncAllowWalletDataInTransportModeWithCustomPassphrase{
 const base::Feature kSyncClearDataOnPassphraseEncryption{
     "ClearSyncDataOnPassphraseEncryption", base::FEATURE_DISABLED_BY_DEFAULT};
 
+// For each below, if enabled, the SyncableService implementation of the
+// corresponding datatype(s) is wrapped within the USS architecture.
+const base::Feature kSyncPseudoUSSAppList{"SyncPseudoUSSAppList",
+                                          base::FEATURE_DISABLED_BY_DEFAULT};
+const base::Feature kSyncPseudoUSSApps{"SyncPseudoUSSApps",
+                                       base::FEATURE_DISABLED_BY_DEFAULT};
+const base::Feature kSyncPseudoUSSDictionary{"SyncPseudoUSSDictionary",
+                                             base::FEATURE_DISABLED_BY_DEFAULT};
+const base::Feature kSyncPseudoUSSExtensions{"SyncPseudoUSSExtensions",
+                                             base::FEATURE_DISABLED_BY_DEFAULT};
+const base::Feature kSyncPseudoUSSFavicons{"SyncPseudoUSSFavicons",
+                                           base::FEATURE_DISABLED_BY_DEFAULT};
+const base::Feature kSyncPseudoUSSPreferences{
+    "SyncPseudoUSSPreferences", base::FEATURE_DISABLED_BY_DEFAULT};
+const base::Feature kSyncPseudoUSSPriorityPreferences{
+    "SyncPseudoUSSPriorityPreferences", base::FEATURE_DISABLED_BY_DEFAULT};
+const base::Feature kSyncPseudoUSSThemes{"SyncPseudoUSSThemes",
+                                         base::FEATURE_DISABLED_BY_DEFAULT};
+
 // If enabled, allows the Sync machinery ("transport layer") to start
 // independently of Sync-the-feature.
 const base::Feature kSyncStandaloneTransport{"SyncStandaloneTransport",

components/sync/driver/sync_driver_switches.h

@@ -23,6 +23,14 @@ extern const char kSyncShortNudgeDelayForTest[];
 extern const base::Feature
     kSyncAllowWalletDataInTransportModeWithCustomPassphrase;
 extern const base::Feature kSyncClearDataOnPassphraseEncryption;
+extern const base::Feature kSyncPseudoUSSAppList;
+extern const base::Feature kSyncPseudoUSSApps;
+extern const base::Feature kSyncPseudoUSSDictionary;
+extern const base::Feature kSyncPseudoUSSExtensions;
+extern const base::Feature kSyncPseudoUSSFavicons;
+extern const base::Feature kSyncPseudoUSSPreferences;
+extern const base::Feature kSyncPseudoUSSPriorityPreferences;
+extern const base::Feature kSyncPseudoUSSThemes;
 extern const base::Feature kSyncStandaloneTransport;
 extern const base::Feature kSyncSupportSecondaryAccount;
 extern const base::Feature kSyncUserEvents;

components/sync/driver/syncable_service_based_model_type_controller.cc

+// 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 "components/sync/driver/syncable_service_based_model_type_controller.h"
+
+#include <utility>
+
+#include "components/sync/model_impl/client_tag_based_model_type_processor.h"
+#include "components/sync/model_impl/forwarding_model_type_controller_delegate.h"
+#include "components/sync/model_impl/syncable_service_based_bridge.h"
+
+namespace syncer {
+
+namespace {
+
+// Similar to ForwardingModelTypeControllerDelegate, but allows evaluating the
+// reference to SyncableService in a lazy way, which is convenient for tests.
+class ControllerDelegate : public ModelTypeControllerDelegate {
+ public:
+  using SyncableServiceProvider =
+      SyncableServiceBasedModelTypeController::SyncableServiceProvider;
+
+  ControllerDelegate(ModelType type,
+                     OnceModelTypeStoreFactory store_factory,
+                     SyncableServiceProvider syncable_service_provider)
+      : type_(type),
+        store_factory_(std::move(store_factory)),
+        syncable_service_provider_(std::move(syncable_service_provider)) {
+    DCHECK(store_factory_);
+    DCHECK(syncable_service_provider_);
+  }
+
+  ~ControllerDelegate() override {}
+
+  void OnSyncStarting(const DataTypeActivationRequest& request,
+                      StartCallback callback) override {
+    BuildOrGetBridgeDelegate()->OnSyncStarting(request, std::move(callback));
+  }
+
+  void OnSyncStopping(SyncStopMetadataFate metadata_fate) override {
+    BuildOrGetBridgeDelegate()->OnSyncStopping(metadata_fate);
+  }
+
+  void GetAllNodesForDebugging(AllNodesCallback callback) override {
+    BuildOrGetBridgeDelegate()->GetAllNodesForDebugging(std::move(callback));
+  }
+
+  void GetStatusCountersForDebugging(StatusCountersCallback callback) override {
+    BuildOrGetBridgeDelegate()->GetStatusCountersForDebugging(
+        std::move(callback));
+  }
+
+  void RecordMemoryUsageAndCountsHistograms() override {
+    BuildOrGetBridgeDelegate()->RecordMemoryUsageAndCountsHistograms();
+  }
+
+ private:
+  ModelTypeControllerDelegate* BuildOrGetBridgeDelegate() {
+    if (!bridge_) {
+      base::WeakPtr<SyncableService> syncable_service =
+          std::move(syncable_service_provider_).Run();
+      DCHECK(syncable_service);
+      bridge_ = std::make_unique<SyncableServiceBasedBridge>(
+          type_, std::move(store_factory_),
+          std::make_unique<ClientTagBasedModelTypeProcessor>(
+              type_,
+              /*dump_stack=*/base::RepeatingClosure()),
+          syncable_service.get());
+    }
+    return bridge_->change_processor()->GetControllerDelegate().get();
+  }
+
+  const ModelType type_;
+  OnceModelTypeStoreFactory store_factory_;
+  SyncableServiceProvider syncable_service_provider_;
+  std::unique_ptr<ModelTypeSyncBridge> bridge_;
+
+  DISALLOW_COPY_AND_ASSIGN(ControllerDelegate);
+};
+
+}  // namespace
+
+SyncableServiceBasedModelTypeController::
+    SyncableServiceBasedModelTypeController(
+        ModelType type,
+        OnceModelTypeStoreFactory store_factory,
+        SyncableServiceProvider syncable_service_provider)
+    : ModelTypeController(type,
+                          std::make_unique<ControllerDelegate>(
+                              type,
+                              std::move(store_factory),
+                              std::move(syncable_service_provider))) {}
+
+SyncableServiceBasedModelTypeController::
+    ~SyncableServiceBasedModelTypeController() {}
+
+}  // namespace syncer

components/sync/driver/syncable_service_based_model_type_controller.h

+// 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 COMPONENTS_SYNC_DRIVER_SYNCABLE_SERVICE_BASED_MODEL_TYPE_CONTROLLER_H_
+#define COMPONENTS_SYNC_DRIVER_SYNCABLE_SERVICE_BASED_MODEL_TYPE_CONTROLLER_H_
+
+#include <memory>
+
+#include "base/callback_forward.h"
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "components/sync/base/model_type.h"
+#include "components/sync/driver/model_type_controller.h"
+#include "components/sync/model/model_type_store.h"
+
+namespace syncer {
+
+class SyncableService;
+
+// Controller responsible for integrating SyncableService implementations within
+// a non-blocking datatype (USS).
+class SyncableServiceBasedModelTypeController : public ModelTypeController {
+ public:
+  using SyncableServiceProvider =
+      base::OnceCallback<base::WeakPtr<syncer::SyncableService>()>;
+
+  SyncableServiceBasedModelTypeController(
+      ModelType type,
+      OnceModelTypeStoreFactory store_factory,
+      SyncableServiceProvider syncable_service_provider);
+  ~SyncableServiceBasedModelTypeController() override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(SyncableServiceBasedModelTypeController);
+};
+
+}  // namespace syncer
+
+#endif  // COMPONENTS_SYNC_DRIVER_SYNCABLE_SERVICE_BASED_MODEL_TYPE_CONTROLLER_H_