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
void TreeView::Expand(TreeModelNode* node) {
  DCHECK(model_ && node);
  if (!root_shown_ && model_->GetRoot() == node) {
    return;
  }
  TreeModelNode* parent = model_->GetParent(node);
  if (parent) {
    Expand(parent);
  }
  TreeView_Expand(tree_view_, GetNodeDetails(node)->tree_item, TVE_EXPAND);
}

void TreeView::Expand(TreeModelNode* node) {
  DCHECK(model_ && node);
  if (!root_shown_ && model_->GetRoot() == node) {
    return;
  }
  TreeModelNode* parent = model_->GetParent(node);
  if (parent) {
    Expand(parent);
  }
  TreeView_Expand(tree_view_, GetNodeDetails(node)->tree_item, TVE_EXPAND);
}
