[Sync] Erase sync DB when corrupted

sync/syncable/directory_unittest.cc

Index: sync/syncable/directory_unittest.cc
diff --git a/sync/syncable/directory_unittest.cc b/sync/syncable/directory_unittest.cc
index d802d4f2ccf5624e6af0dba22d1d4dbac748d52c..690af4ff4d6993b190872508f07e230f6db2296a 100644
--- a/sync/syncable/directory_unittest.cc
+++ b/sync/syncable/directory_unittest.cc
@@ -12,6 +12,7 @@
 #include "sync/syncable/syncable_write_transaction.h"
 #include "sync/test/engine/test_syncable_utils.h"
 #include "sync/test/test_directory_backing_store.h"
+#include "sync/util/mock_unrecoverable_error_handler.h"
 
 using base::ExpectDictBooleanValue;
 using base::ExpectDictStringValue;
@@ -2030,6 +2031,25 @@ TEST_F(SyncableDirectoryTest, SaveChangesSnapshot_HasUnsavedMetahandleChanges) {
   snapshot.delete_journals_to_purge.clear();
 }
 
+// Verify that Directory triggers an unrecoverable error when a catastrophic
+// DirectoryBackingStore error is detected.
+TEST_F(SyncableDirectoryTest, CatastrophicError) {
+  MockUnrecoverableErrorHandler unrecoverable_error_handler;
+  Directory dir(new InMemoryDirectoryBackingStore("catastrophic_error"),
+                &unrecoverable_error_handler, nullptr, nullptr, nullptr);
+  ASSERT_EQ(OPENED, dir.Open(kDirectoryName, directory_change_delegate(),
+                             NullTransactionObserver()));
+  ASSERT_EQ(0, unrecoverable_error_handler.invocation_count());
+
+  // Fire off two catastrophic errors. Call it twice to ensure Directory is
+  // tolerant of multiple invocations since that may happen in the real world.
+  dir.OnCatastrophicError();
+  dir.OnCatastrophicError();
+
+  // See that the unrecoverable error handler has been invoked twice.
+  ASSERT_EQ(2, unrecoverable_error_handler.invocation_count());
+}
+
 }  // namespace syncable
 
 }  // namespace syncer