[Sync] Renaming client key to client tag.

sync/api/model_type_change_processor.h

Index: sync/api/model_type_change_processor.h
diff --git a/sync/api/model_type_change_processor.h b/sync/api/model_type_change_processor.h
index bbfe16cd37ab4d8880078f68efb50fd05b4612b2..06a0f8f683dc939e2c0f62f50233fbd998aef093 100644
--- a/sync/api/model_type_change_processor.h
+++ b/sync/api/model_type_change_processor.h
@@ -30,12 +30,12 @@ class SYNC_EXPORT ModelTypeChangeProcessor {
   // does not need to be fully set, but it should at least have specifics and
   // non-unique name. The processor will fill in the rest if the service does
   // not have a reason to care.
-  virtual void Put(const std::string& client_key,
+  virtual void Put(const std::string& client_tag,
                    scoped_ptr<EntityData> entity_data,
                    MetadataChangeList* metadata_change_list) = 0;
 
   // Inform the processor of a deleted entity.
-  virtual void Delete(const std::string& client_key,
+  virtual void Delete(const std::string& client_tag,
                       MetadataChangeList* metadata_change_list) = 0;
 };