[Sync] Add support for proxy types

sync/syncable/model_type.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/internal_api/public/base/model_type.h"
 
 #include "base/string_split.h"
 #include "base/values.h"
 #include "sync/protocol/app_notification_specifics.pb.h"
 #include "sync/protocol/app_setting_specifics.pb.h"
@@ skipping 272 matching lines @@
   }
   return set;
 }
 
 ModelTypeSet EncryptableUserTypes() {
   ModelTypeSet encryptable_user_types = UserTypes();
   // We never encrypt history delete directives.
   encryptable_user_types.Remove(HISTORY_DELETE_DIRECTIVES);
   // Synced notifications are not encrypted since the server must see changes.
   encryptable_user_types.Remove(SYNCED_NOTIFICATIONS);
+  // Virtual types have no sync representation and are therefore not encrypted
+  // either. Their underlying representations may or may not be encrypted
+  // though.
+  encryptable_user_types.RemoveAll(VirtualTypes());
   return encryptable_user_types;
 }
 
 ModelTypeSet ControlTypes() {
   ModelTypeSet set;
   for (int i = FIRST_CONTROL_MODEL_TYPE; i <= LAST_CONTROL_MODEL_TYPE; ++i) {
     set.Put(ModelTypeFromInt(i));
   }
 
   // TODO(albertb): Re-enable this when the server supports it.
   set.Remove(PRIORITY_PREFERENCES);
 
   return set;
 }
 
+ModelTypeSet VirtualTypes() {
+  ModelTypeSet set;
+  // TODO(zea): add a TABS type here.
+  return set;
+}
+
 bool IsControlType(ModelType model_type) {
   return ControlTypes().Has(model_type);
 }
 
 const char* ModelTypeToString(ModelType model_type) {
   // This is used in serialization routines as well as for displaying debug
   // information.  Do not attempt to change these string values unless you know
   // what you're doing.
   switch (model_type) {
     case TOP_LEVEL_FOLDER:
@@ skipping 353 matching lines @@
   }
   *model_type = UNSPECIFIED;
   return false;
 }
 
 bool IsRealDataType(ModelType model_type) {
   return model_type >= FIRST_REAL_MODEL_TYPE && model_type < MODEL_TYPE_COUNT;
 }
 
 }  // namespace syncer