[Sync] Erase sync DB when corrupted

sync/BUILD.gn

Index: sync/BUILD.gn
diff --git a/sync/BUILD.gn b/sync/BUILD.gn
index 6b106dda03c6eb8cc6327ca12a6e24916adaafcd..05585ea7b7a2bd6b1a576215f903f8535d915492 100644
--- a/sync/BUILD.gn
+++ b/sync/BUILD.gn
@@ -442,6 +442,8 @@ static_library("test_support_sync_core") {
     "sessions/test_util.cc",
     "sessions/test_util.h",
     "test/callback_counter.h",
+    "test/directory_backing_store_corruption_testing.cc",
+    "test/directory_backing_store_corruption_testing.h",
     "test/engine/fake_model_worker.cc",
     "test/engine/fake_model_worker.h",
     "test/engine/fake_sync_scheduler.cc",
@@ -486,6 +488,8 @@ static_library("test_support_sync_core") {
     "test/test_transaction_observer.h",
     "test/trackable_mock_invalidation.cc",
     "test/trackable_mock_invalidation.h",
+    "util/mock_unrecoverable_error_handler.cc",
+    "util/mock_unrecoverable_error_handler.h",
     "util/test_unrecoverable_error_handler.cc",
     "util/test_unrecoverable_error_handler.h",
   ]