views: add layout delegates

ui/views/view.cc

Index: ui/views/view.cc
diff --git a/ui/views/view.cc b/ui/views/view.cc
index 51d246f0a3fdd6fe91bdc5a351f06909c558287b..128127178dc8a7f549f185f6f81ae76b7c4373a7 100644
--- a/ui/views/view.cc
+++ b/ui/views/view.cc
@@ -568,6 +568,20 @@ void View::SetLayoutManager(LayoutManager* layout_manager) {
     layout_manager_->Installed(this);
 }
 
+static LayoutDelegate default_layout_delegate_;
+
+LayoutDelegate* View::GetLayoutDelegate() const {
+  if (layout_delegate_)
+    return layout_delegate_;
+  if (!parent_)
+    return &default_layout_delegate_;
+  return parent_->GetLayoutDelegate();
+}
+
+void View::SetLayoutDelegate(LayoutDelegate* delegate) {
+  layout_delegate_ = delegate;
+}
+
 void View::SnapLayerToPixelBoundary() {
   if (!layer())
     return;