Introduce the plumbing necessary to report Unrecoverable error from model safe workers.

chrome/browser/sync/sessions/unrecoverable_error_info.h

+// Copyright (c) 2011 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 CHROME_BROWSER_SYNC_SESSIONS_UNRECOVERABLE_ERROR_INFO_H_
+#define CHROME_BROWSER_SYNC_SESSIONS_UNRECOVERABLE_ERROR_INFO_H_
+// TODO(lipalani): Figure out the right location for this class so it is
+// accessible outside of sync engine as well.
+#pragma once
+
+#include <string>
+
+#include "base/location.h"
+
+namespace browser_sync {
+namespace sessions {
+
+class UnrecoverableErrorInfo {
+ public:
+  UnrecoverableErrorInfo();
+  UnrecoverableErrorInfo(
+    const tracked_objects::Location& location,
+    const std::string& message);
+  ~UnrecoverableErrorInfo();
+
+  void Reset(const tracked_objects::Location& location,
+             const std::string& message);
+
+  bool IsSet() const;
+
+  const tracked_objects::Location& location() const;
+  const std::string& message() const;
+
+ private:
+  tracked_objects::Location location_;
+  std::string message_;
+  bool is_set_;
+};
+
+}  // namespace sessions
+}  // namespace browser_sync
+
+#endif  // CHROME_BROWSER_SYNC_SESSIONS_UNRECOVERABLE_ERROR_INFO_H_