[Sync] Erase sync DB when corrupted

sync/test/directory_backing_store_corruption_testing.h

Index: sync/test/directory_backing_store_corruption_testing.h
diff --git a/sync/test/directory_backing_store_corruption_testing.h b/sync/test/directory_backing_store_corruption_testing.h
new file mode 100644
index 0000000000000000000000000000000000000000..5897ec0466d28d072ffdbb774e7120a010af3155
--- /dev/null
+++ b/sync/test/directory_backing_store_corruption_testing.h
@@ -0,0 +1,27 @@
+// Copyright 2015 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 SYNC_TEST_DIRECTORY_BACKING_STORE_CORRUPTION_TESTING_H_
+#define SYNC_TEST_DIRECTORY_BACKING_STORE_CORRUPTION_TESTING_H_
+
+#include "base/files/file_path.h"
+
+namespace syncer {
+namespace syncable {
+namespace corruption_testing {
+
+// The number of DB entries required to reliably trigger detectable corruption
+// using |CorruptDatabase|.
+extern const int kNumEntriesRequiredForCorruption;

[Nicolas Zea, 2015/04/27 19:17:32]

any reason you don't just define the constant here?

[maniscalco, 2015/04/27 19:51:17]

If the value were defined in the header file, then each .o file could end up
with its own copy of the value (potentially causing binary bloat).  By declaring
extern in the .h and defining in the .cc, I can be sure there is only one copy
of the value.

+
+// Corrupt the sync database at |backing_file_path|.
+//
+// Returns true if the database was successfully corrupted.
+bool CorruptDatabase(const base::FilePath& backing_file_path);
+
+}  // namespace corruption_util
+}  // namespace syncable
+}  // namespace syncer
+
+#endif  // SYNC_TEST_DIRECTORY_BACKING_STORE_CORRUPTION_TESTING_H_