    // view hierarchy. We add this view as embedder's child here.
    // This would go in WebContentsViewGuest::CreateView, but that is too early to
    // access embedder_web_contents(). Therefore, we do it here.
-+  if (parent_view->GetNativeView() != platform_view_->GetNativeView())
-   parent_view->GetNativeView()->AddChild(platform_view_->GetNativeView());
+   if (!base::FeatureList::IsEnabled(features::kMash))
+-    parent_view->GetNativeView()->AddChild(platform_view_->GetNativeView());
++    if (parent_view->GetNativeView() != platform_view_->GetNativeView())
++      parent_view->GetNativeView()->AddChild(platform_view_->GetNativeView());
  #endif  // defined(USE_AURA)
  }
  

diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index cf3733f..065df39 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -1581,6 +1581,12 @@ void WebContentsImpl::Init(const WebContents::CreateParams& params) {
   std::string unique_name;
   frame_tree_.root()->SetFrameName(params.main_frame_name, unique_name);
 

 
 RenderWidgetHostViewBase* WebContentsViewGuest::CreateViewForPopupWidget(
diff --git a/content/public/browser/web_contents.h b/content/public/browser/web_contents.h
index a13db5f4dd61..621124decfdc 100644
--- a/content/public/browser/web_contents.h
+++ b/content/public/browser/web_contents.h
@@ -69,9 +69,12 @@ class BrowserPluginGuestDelegate;
 class InterstitialPage;
 class RenderFrameHost;
 class RenderViewHost;
+class RenderViewHostDelegateView;
