[Sync] Add support for dynamically enabling/disabling types

sync/api/sync_error.cc

 // Copyright (c) 2012 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 "sync/api/sync_error.h"
 
 #include <ostream>
 
 #include "base/location.h"
 #include "base/logging.h"
@@ skipping 16 matching lines @@
       break;
     case DATATYPE_ERROR:
       type_message = "datatype error was encountered: ";
       break;
     case PERSISTENCE_ERROR:
       type_message = "persistence error was encountered: ";
       break;
     case CRYPTO_ERROR:
       type_message = "cryptographer error was encountered: ";
       break;
-    default:
-      NOTREACHED();
-      type_message = "invalid error: ";
+    case UNREADY_ERROR:
+      type_message = "unready error was encountered: ";
+      break;
+    case UNSET:
+      NOTREACHED() << "Invalid error type";
+      return;
   }
   Init(location, type_message + custom_message, model_type, error_type);
   PrintLogError();
 }
 
 SyncError::SyncError(const SyncError& other) {
   Copy(other);
 }
 
 SyncError::~SyncError() {
@@ skipping 81 matching lines @@
                                   logging::LOG_ERROR).stream(),
               LOG_IS_ON(ERROR))
       << ModelTypeToString(model_type_) << " " << message_;
 }
 
 void PrintTo(const SyncError& sync_error, std::ostream* os) {
   *os << sync_error.ToString();
 }
 
 }  // namespace syncer