[Sync] Add HasChildren() function and use it instead of GetFirstChildId()

chrome/browser/sync/internal_api/base_node.cc

Index: chrome/browser/sync/internal_api/base_node.cc
diff --git a/chrome/browser/sync/internal_api/base_node.cc b/chrome/browser/sync/internal_api/base_node.cc
index c409b8a0d9bfc2054e26bc24d2e45ee6ea9c0b5b..2aa212c98aab427db77e477521e3f75db3e9b184 100644
--- a/chrome/browser/sync/internal_api/base_node.cc
+++ b/chrome/browser/sync/internal_api/base_node.cc
@@ -201,6 +201,12 @@ GURL BaseNode::GetURL() const {
   return GURL(GetBookmarkSpecifics().url());
 }
 
+bool BaseNode::HasChildren() const {
+  syncable::Directory* dir = GetTransaction()->GetLookup();
+  syncable::BaseTransaction* trans = GetTransaction()->GetWrappedTrans();
+  return dir->HasChildren(trans, GetEntry()->Get(syncable::ID));
+}
+
 int64 BaseNode::GetPredecessorId() const {
   syncable::Id id_string = GetEntry()->Get(syncable::PREV_ID);
   if (id_string.IsRoot())