[Sync] Erase sync DB when corrupted

sync/util/mock_unrecoverable_error_handler.cc

Index: sync/util/mock_unrecoverable_error_handler.cc
diff --git a/sync/util/mock_unrecoverable_error_handler.cc b/sync/util/mock_unrecoverable_error_handler.cc
new file mode 100644
index 0000000000000000000000000000000000000000..bfed1f1e0cbabed30c4fe86a4cab24eaec8544ae
--- /dev/null
+++ b/sync/util/mock_unrecoverable_error_handler.cc
@@ -0,0 +1,26 @@
+// 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.
+
+#include "sync/util/mock_unrecoverable_error_handler.h"
+
+namespace syncer {
+
+MockUnrecoverableErrorHandler::MockUnrecoverableErrorHandler()
+    : invocation_count_(0) {
+}
+
+MockUnrecoverableErrorHandler::~MockUnrecoverableErrorHandler() {
+}
+
+void MockUnrecoverableErrorHandler::OnUnrecoverableError(
+    const tracked_objects::Location& from_here,
+    const std::string& message) {
+  ++invocation_count_;
+}
+
+int MockUnrecoverableErrorHandler::invocation_count() const {
+  return invocation_count_;
+}
+
+}  // namespace syncer