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

chrome/browser/sync/js/js_sync_manager_observer.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_JS_JS_SYNC_MANAGER_OBSERVER_H_
 #define CHROME_BROWSER_SYNC_JS_JS_SYNC_MANAGER_OBSERVER_H_
 #pragma once
 
 #include <string>
 
@@ skipping 31 matching lines @@
       const std::string& bootstrap_token) OVERRIDE;
   virtual void OnEncryptionComplete(
       const syncable::ModelTypeSet& encrypted_types) OVERRIDE;
   virtual void OnInitializationComplete(
       const WeakHandle<JsBackend>& js_backend, bool success) OVERRIDE;
   virtual void OnStopSyncingPermanently() OVERRIDE;
   virtual void OnClearServerDataSucceeded() OVERRIDE;
   virtual void OnClearServerDataFailed() OVERRIDE;
   virtual void OnActionableError(
       const browser_sync::SyncProtocolError& sync_protocol_error) OVERRIDE;
+  virtual void OnUnrecoverableError(const tracked_objects::Location& location,
+      const std::string& message) OVERRIDE;
 
  private:
   void HandleJsEvent(const tracked_objects::Location& from_here,
                     const std::string& name, const JsEventDetails& details);
 
   WeakHandle<JsEventHandler> event_handler_;
 
   DISALLOW_COPY_AND_ASSIGN(JsSyncManagerObserver);
 };
 
 }  // namespace browser_sync
 
 #endif  // CHROME_BROWSER_SYNC_JS_JS_SYNC_MANAGER_OBSERVER_H_