[sync] Extend send-tab-to-self ModelTypeControllers for transport mode

This CL extends the MTC of the SEND_TAB_TO_SELF data type to receive a
ModelTypeControllerDelegate for transport-only mode. A non-null
delegate is passed to the controller if and only if the existing
kSendTabToSelfWhenSignedIn feature toggle is enabled.

Bug: 956722
Change-Id: Ie14535d0e873cc8a3c8bcfedc611f8d8eb6abaa5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2517584
Commit-Queue: Victor Vianna <victorvianna@google.com>
Reviewed-by: Marc Treib <treib@chromium.org>
Reviewed-by: sebsg <sebsg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#824025}

components/browser_sync/profile_sync_components_factory_impl.cc

@@ -27,6 +27,7 @@
 #include "components/password_manager/core/browser/sync/password_model_type_controller.h"
 #include "components/prefs/pref_service.h"
 #include "components/reading_list/features/reading_list_switches.h"
+#include "components/send_tab_to_self/features.h"
 #include "components/send_tab_to_self/send_tab_to_self_model_type_controller.h"
 #include "components/send_tab_to_self/send_tab_to_self_sync_service.h"
 #include "components/sync/base/legacy_directory_deletion.h"
@@ -362,13 +363,22 @@ ProfileSyncComponentsFactoryImpl::CreateCommonDataTypeControllers(
   }
 
   if (!disabled_types.Has(syncer::SEND_TAB_TO_SELF)) {
+    syncer::ModelTypeControllerDelegate* delegate =
+        sync_client_->GetSendTabToSelfSyncService()
+            ->GetControllerDelegate()
+            .get();
     controllers.push_back(
         std::make_unique<send_tab_to_self::SendTabToSelfModelTypeController>(
             sync_service,
+            /*delegate_for_full_sync_mode=*/
             std::make_unique<syncer::ForwardingModelTypeControllerDelegate>(
-                sync_client_->GetSendTabToSelfSyncService()
-                    ->GetControllerDelegate()
-                    .get())));
+                delegate),
+            /*delegate_for_transport_mode=*/
+            base::FeatureList::IsEnabled(
+                send_tab_to_self::kSendTabToSelfWhenSignedIn)
+                ? std::make_unique<
+                      syncer::ForwardingModelTypeControllerDelegate>(delegate)
+                : nullptr));
   }
 
   if (!disabled_types.Has(syncer::USER_CONSENTS)) {

components/send_tab_to_self/send_tab_to_self_model_type_controller.cc

@@ -7,6 +7,7 @@
 #include <utility>
 
 #include "base/feature_list.h"
+#include "components/send_tab_to_self/features.h"
 #include "components/sync/driver/sync_auth_util.h"
 #include "components/sync/driver/sync_service.h"
 #include "google_apis/gaia/google_service_auth_error.h"
@@ -15,9 +16,17 @@ namespace send_tab_to_self {
 
 SendTabToSelfModelTypeController::SendTabToSelfModelTypeController(
     syncer::SyncService* sync_service,
-    std::unique_ptr<syncer::ModelTypeControllerDelegate> delegate)
-    : ModelTypeController(syncer::SEND_TAB_TO_SELF, std::move(delegate)),
+    std::unique_ptr<syncer::ModelTypeControllerDelegate>
+        delegate_for_full_sync_mode,
+    std::unique_ptr<syncer::ModelTypeControllerDelegate>
+        delegate_for_transport_mode)
+    : ModelTypeController(syncer::SEND_TAB_TO_SELF,
+                          std::move(delegate_for_full_sync_mode),
+                          std::move(delegate_for_transport_mode)),
       sync_service_(sync_service) {
+  DCHECK_EQ(base::FeatureList::IsEnabled(
+                send_tab_to_self::kSendTabToSelfWhenSignedIn),
+            ShouldRunInTransportOnlyMode());
   // TODO(crbug.com/906995): Remove this observing mechanism once all sync
   // datatypes are stopped by ProfileSyncService, when sync is paused.
   sync_service_->AddObserver(this);

components/send_tab_to_self/send_tab_to_self_model_type_controller.h

@@ -19,11 +19,15 @@ namespace send_tab_to_self {
 class SendTabToSelfModelTypeController : public syncer::ModelTypeController,
                                          public syncer::SyncServiceObserver {
  public:
-  // The |delegate| and |sync_service| must not be null. Furthermore,
-  // |sync_service| must outlive this object.
+  // The |delegate_for_full_sync_mode| and |sync_service| must not be null.
+  // |delegate_for_transport_mode| can be null. |sync_service| must outlive this
+  // object.
   SendTabToSelfModelTypeController(
       syncer::SyncService* sync_service,
-      std::unique_ptr<syncer::ModelTypeControllerDelegate> delegate);
+      std::unique_ptr<syncer::ModelTypeControllerDelegate>
+          delegate_for_full_sync_mode,
+      std::unique_ptr<syncer::ModelTypeControllerDelegate>
+          delegate_for_transport_mode);
   ~SendTabToSelfModelTypeController() override;
 
   // DataTypeController overrides.