[Sync] Add support for enabling session sync remotely.

chrome/browser/sync/internal_api/sync_manager.cc

 // Copyright (c) 2011 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/internal_api/sync_manager.h"
 
 #include <string>
 #include <vector>
 
 #include "base/base64.h"
@@ skipping 1950 matching lines @@
 UserShare* SyncManager::GetUserShare() const {
   return data_->GetUserShare();
 }
 
 void SyncManager::RefreshEncryption() {
   if (data_->UpdateCryptographerFromNigori())
     data_->EncryptDataTypes(syncable::ModelTypeSet());
 }
 
 syncable::ModelTypeSet SyncManager::GetEncryptedDataTypes() const {
-  sync_api::ReadTransaction trans(FROM_HERE, GetUserShare());
+  ReadTransaction trans(FROM_HERE, GetUserShare());
   return GetEncryptedTypes(&trans);
 }
 
+bool SyncManager::ReceivedExperimentalTypes(syncable::ModelTypeSet* to_add)
+    const {
+  ReadTransaction trans(FROM_HERE, GetUserShare());
+  ReadNode node(&trans);
+  if (!node.InitByTagLookup(kNigoriTag)) {
+    VLOG(1) << "Couldn't find Nigori node.";
+    return false;
+  }
+  if (node.GetNigoriSpecifics().sync_tabs()) {
+    to_add->insert(syncable::SESSIONS);
+    return true;
+  }
+  return false;
+}
+
 bool SyncManager::HasUnsyncedItems() const {
   sync_api::ReadTransaction trans(FROM_HERE, GetUserShare());
   return (trans.GetWrappedTrans()->directory()->unsynced_entity_count() != 0);
 }
 
 void SyncManager::LogUnsyncedItems(int level) const {
   std::vector<int64> unsynced_handles;
   sync_api::ReadTransaction trans(FROM_HERE, GetUserShare());
   trans.GetWrappedTrans()->directory()->GetUnsyncedMetaHandles(
       trans.GetWrappedTrans(), &unsynced_handles);
@@ skipping 54 matching lines @@
 
   for (syncable::ModelTypeSet::const_iterator i = types.begin();
        i != types.end(); ++i) {
     if (!lookup->initial_sync_ended_for_type(*i))
       return false;
   }
   return true;
 }
 
 }  // namespace sync_api