[Sync] Erase sync DB when corrupted

sync/util/mock_unrecoverable_error_handler.h

+// 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_UTIL_MOCK_UNRECOVERABLE_ERROR_HANDLER_H_
+#define SYNC_UTIL_MOCK_UNRECOVERABLE_ERROR_HANDLER_H_
+
+#include <string>
+
+#include "base/macros.h"
+#include "sync/internal_api/public/util/unrecoverable_error_handler.h"
+
+namespace syncer {
+
+// Mock implementation of UnrecoverableErrorHandler that counts how many times
+// it has been invoked.
+class MockUnrecoverableErrorHandler : public UnrecoverableErrorHandler {
+ public:
+  MockUnrecoverableErrorHandler();
+  ~MockUnrecoverableErrorHandler() override;
+  void OnUnrecoverableError(const tracked_objects::Location& from_here,
+                            const std::string& message) override;
+
+  // Returns the number of times this handler has been invoked.
+  int invocation_count() const;
+
+ private:
+  int invocation_count_;
+
+  DISALLOW_COPY_AND_ASSIGN(MockUnrecoverableErrorHandler);
+};
+
+}  // namespace syncer
+
+#endif  // SYNC_UTIL_MOCK_UNRECOVERABLE_ERROR_HANDLER_H_