[Sync] Add priority preferences datatype for mobile

chrome/browser/sync/profile_sync_service.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 "chrome/browser/sync/profile_sync_service.h"
 
 #include <cstddef>
 #include <map>
 #include <vector>
 
@@ skipping 1765 matching lines @@
   if (directory_data_type_manager_.get())
     directory_data_type_manager_->ResetDataTypeErrors();
   ChangePreferredDataTypes(chosen_types);
 }
 
 void ProfileSyncService::ChangePreferredDataTypes(
     syncer::ModelTypeSet preferred_types) {
 
   DVLOG(1) << "ChangePreferredDataTypes invoked";
   const syncer::ModelTypeSet registered_types = GetRegisteredDataTypes();
-  const syncer::ModelTypeSet registered_preferred_types =
-      Intersection(registered_types, preferred_types);
-  sync_prefs_.SetPreferredDataTypes(registered_types,
-                                    registered_preferred_types);
+  // Will only enable those types that are registered and preferred.
+  sync_prefs_.SetPreferredDataTypes(registered_types, preferred_types);
 
   // Now reconfigure the DTM.
   ReconfigureDatatypeManager();
 
   // TODO(rlarocque): Reconfigure the NonBlockingDataTypeManager, too.  Blocked
   // on crbug.com/368834.  Until that bug is fixed, it's difficult to tell
   // which types should be enabled and when.
 }
 
 syncer::ModelTypeSet ProfileSyncService::GetActiveDataTypes() const {
@@ skipping 957 matching lines @@
     } else {
       UMA_HISTOGRAM_COUNTS("Sync.MemoryPressureWarningBeforeCleanShutdown",
                            warning_received);
     }
   }
   sync_prefs_.SetMemoryPressureWarningCount(0);
   // Will set to true during a clean shutdown, so crash or something else will
   // remain this as false.
   sync_prefs_.SetCleanShutdown(false);
 }