[Sync] Add support for proxy types

sync/syncable/directory.cc

Index: sync/syncable/directory.cc
diff --git a/sync/syncable/directory.cc b/sync/syncable/directory.cc
index 7b583647072792ad310c52e74d33a566ab83f673..15ff4e3f08ecd1bfd1a622a5d2760e2ac08fc71d 100644
--- a/sync/syncable/directory.cc
+++ b/sync/syncable/directory.cc
@@ -82,7 +82,10 @@ void Directory::InitKernelForTest(
 Directory::PersistedKernelInfo::PersistedKernelInfo()
     : next_id(0) {
   for (int i = FIRST_REAL_MODEL_TYPE; i < MODEL_TYPE_COUNT; ++i) {
-    reset_download_progress(ModelTypeFromInt(i));
+    ModelType type = ModelTypeFromInt(i);
+    if (VirtualTypes().Has(type))
+      continue;
+    reset_download_progress(type);
     transaction_version[i] = 0;
   }
 }
@@ -564,6 +567,7 @@ bool Directory::VacuumAfterSaveChanges(const SaveChangesSnapshot& snapshot) {
 bool Directory::PurgeEntriesWithTypeIn(ModelTypeSet types,
                                        ModelTypeSet types_to_journal) {
   DCHECK(types.HasAll(types_to_journal));
+  types.RemoveAll(VirtualTypes());
 
   if (types.Empty())
     return true;
@@ -704,7 +708,8 @@ void Directory::IncrementTransactionVersion(ModelType type) {
 
 ModelTypeSet Directory::InitialSyncEndedTypes() {
   syncable::ReadTransaction trans(FROM_HERE, this);
-  const ModelTypeSet all_types = ModelTypeSet::All();
+  ModelTypeSet all_types = ModelTypeSet::All();
+  all_types.RemoveAll(VirtualTypes());
   ModelTypeSet initial_sync_ended_types;
   for (ModelTypeSet::Iterator i = all_types.First(); i.Good(); i.Inc()) {
     if (InitialSyncEndedForType(&trans, i.Get())) {