Give the main frame a RenderWidget.

content/renderer/render_frame_impl.cc

Index: content/renderer/render_frame_impl.cc
diff --git a/content/renderer/render_frame_impl.cc b/content/renderer/render_frame_impl.cc
index 7caee93344984e80486850d375bc3161651529fb..c6a8117d65209437fa901c56f9d1298a51c67b55 100644
--- a/content/renderer/render_frame_impl.cc
+++ b/content/renderer/render_frame_impl.cc
@@ -568,13 +568,28 @@ RenderFrameImpl* RenderFrameImpl::FromRoutingID(int routing_id) {
 
 // static
 RenderFrameImpl* RenderFrameImpl::CreateMainFrame(RenderViewImpl* render_view,
-                                                  int32 routing_id) {
+    int32 routing_id,
+    int32 widget_routing_id,
+    int32 surface_id,
+    bool hidden,
+    const blink::WebScreenInfo& screen_info,
+    CompositorDependencies* compositor_deps) {
+  // A main frame RenderFrame must have a RenderWidget.
+  DCHECK_NE(MSG_ROUTING_NONE, widget_routing_id);
+
   RenderFrameImpl* render_frame =
       RenderFrameImpl::Create(render_view, routing_id);
   WebLocalFrame* web_frame =
       WebLocalFrame::create(blink::WebTreeScopeType::Document, render_frame);
   render_frame->SetWebFrame(web_frame);
   render_view->webview()->setMainFrame(web_frame);
+  render_frame->render_widget_ =
+      RenderWidget::CreateForFrame(widget_routing_id, surface_id, hidden,
+                                   screen_info, compositor_deps, web_frame);
+  // TODO(kenrb): Observing shouldn't be necessary when we sort out
+  // WasShown and WasHidden, separating page-level visibility from
+  // frame-level visibility.
+  render_frame->render_widget_->RegisterRenderFrame(render_frame);
   return render_frame;
 }