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

chrome/browser/sync/sessions/unrecoverable_error_info.cc

+// 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.
+
+#include "chrome/browser/sync/sessions/unrecoverable_error_info.h"
+namespace browser_sync {
+namespace sessions {
+UnrecoverableErrorInfo::UnrecoverableErrorInfo() {
+}
+
+UnrecoverableErrorInfo::~UnrecoverableErrorInfo() {
+}
+
+void UnrecoverableErrorInfo::Set(
+    const tracked_objects::Location& location,
+    const std::string& message) {
+  DCHECK(location_.get() == NULL);
+  location_.reset(new tracked_objects::Location(location));
+  message_ = message;
+}
+
+bool UnrecoverableErrorInfo::IsSet() const {
+  return location_.get() != NULL;
+}
+
+const tracked_objects::Location& UnrecoverableErrorInfo::location() const {
+  DCHECK(IsSet());
+  return *location_;
+}
+
+const std::string& UnrecoverableErrorInfo::message() const {
+  return message_;
+}
+
+}  // namespace sessions
+}  // namespace browser_sync