Add OVERRIDE to ui::TreeModelObserver overridden methods.

BUG=None
TEST=None

R=sky@chromium.org

Review URL: http://codereview.chromium.org/7046093

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@88827 0039d316-1c4b-4281-b951-d872f2087c98
TreeView::NodeDetails* TreeView::GetNodeDetails(TreeModelNode* node) {
  DCHECK(node &&
         node_to_details_map_.find(node) != node_to_details_map_.end());
  return node_to_details_map_[node];
}

TreeView::NodeDetails* TreeView::GetNodeDetails(TreeModelNode* node) {
  DCHECK(node &&
         node_to_details_map_.find(node) != node_to_details_map_.end());
  return node_to_details_map_[node];
}
