Added checks to handle unsyncable extensions.

chrome/browser/sync/glue/extension_model_associator.h

 // Copyright (c) 2010 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_GLUE_EXTENSION_MODEL_ASSOCIATOR_H_
 #define CHROME_BROWSER_SYNC_GLUE_EXTENSION_MODEL_ASSOCIATOR_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 37 matching lines @@
     // thread.
   }
 
   // Used by ExtensionChangeProcessor.
   //
   // TODO(akalin): These functions can actually be moved to the
   // ChangeProcessor after some refactoring.
 
   // TODO(akalin): Return an error string instead of just a bool.
   bool OnClientUpdate(const std::string& id);
-  void OnServerUpdate(const sync_pb::ExtensionSpecifics& server_data);
-  void OnServerRemove(const std::string& id);
+
+  // |extension| may be NULL (if the client does not have the
+  // extension installed).
+  void OnServerUpdate(const sync_pb::ExtensionSpecifics& server_data,
+                      Extension* extension);
 
  private:
   // Returns the extension service from |sync_service_|.  Never
   // returns NULL.
   ExtensionsService* GetExtensionsService();
 
-  bool GetExtensionDataFromClient(
-      const std::string& id, sync_pb::ExtensionSpecifics* client_data);
-
   bool GetExtensionDataFromServer(
       const std::string& id, sync_api::WriteTransaction* trans,
       const sync_api::ReadNode& root,
       sync_pb::ExtensionSpecifics* server_data);
 
   // Updates the server data from the given extension data.
   // extension_data->ServerNeedsUpdate() must hold before this
   // function is called.  Returns whether or not the update was
   // successful.  If the update was successful,
   // extension_data->ServerNeedsUpdate() will be false after this
@@ skipping 20 matching lines @@
 
   // Weak pointer.
   ProfileSyncService* sync_service_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionModelAssociator);
 };
 
 }  // namespace browser_sync
 
 #endif  // CHROME_BROWSER_SYNC_GLUE_EXTENSION_MODEL_ASSOCIATOR_H_