Enable RL sync by default on iOS

components/browser_sync/profile_sync_components_factory_impl.cc

Index: components/browser_sync/profile_sync_components_factory_impl.cc
diff --git a/components/browser_sync/profile_sync_components_factory_impl.cc b/components/browser_sync/profile_sync_components_factory_impl.cc
index c4332e02bdc969cd0fa5b05a11bd7e5b61822f33..62bebd611543e536d0a513f5f7660733a1515adb 100644
--- a/components/browser_sync/profile_sync_components_factory_impl.cc
+++ b/components/browser_sync/profile_sync_components_factory_impl.cc
@@ -274,14 +274,17 @@ void ProfileSyncComponentsFactoryImpl::RegisterCommonDataTypes(
         base::MakeUnique<UIDataTypeController>(syncer::ARTICLES, error_callback,
                                                sync_client_));
   }
-  // Reading list sync is disabled by default.  Register only if explicitly
-  // enabled.
-  if (enabled_types.Has(syncer::READING_LIST)) {
+
+#if defined(OS_IOS)

[pavely, 2016/11/20 02:31:58]

Yes, this is a correct way to only enable type on supported platform.
https://cs.chromium.org/chromium/src/chrome/browser/sync/chrome_sync_client.c...

[Olivier, 2016/11/20 10:32:33]

Acknowledged.

+  // Reading list sync is enabled by default only on iOS.  Register unless
+  // explicitly disabled.
+  if (!disabled_types.Has(syncer::READING_LIST)) {
     sync_service->RegisterDataTypeController(
         base::MakeUnique<ModelTypeController>(
             syncer::READING_LIST, error_callback, sync_client_,
             base::ThreadTaskRunnerHandle::Get()));
   }
+#endif
 }
 
 DataTypeManager* ProfileSyncComponentsFactoryImpl::CreateDataTypeManager(