Give the main frame a RenderWidget.

content/renderer/render_widget.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/render_widget.h"
 
 #include "base/auto_reset.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/logging.h"
@@ skipping 569 matching lines @@
     widget->CompleteInit();
     return widget.get();
   }
   return nullptr;
 }
 
 // static
 blink::WebWidget* RenderWidget::CreateWebFrameWidget(
     RenderWidget* render_widget,
     blink::WebLocalFrame* frame) {
+  if (!frame->parent()) {
+    // TODO(dcheng): The main frame widget currently has a special case.
+    // Eliminate this once WebView is no longer a WebWidget.
+    return blink::WebFrameWidget::create(render_widget, frame->view(), frame);
+  }
   return blink::WebFrameWidget::create(render_widget, frame);
 }
 
 // static
 blink::WebWidget* RenderWidget::CreateWebWidget(RenderWidget* render_widget) {
   switch (render_widget->popup_type_) {
     case blink::WebPopupTypeNone:  // Nothing to create.
       break;
     case blink::WebPopupTypePage:
       return WebPagePopup::create(render_widget);
@@ skipping 1842 matching lines @@
 void RenderWidget::RegisterVideoHoleFrame(RenderFrameImpl* frame) {
   video_hole_frames_.AddObserver(frame);
 }
 
 void RenderWidget::UnregisterVideoHoleFrame(RenderFrameImpl* frame) {
   video_hole_frames_.RemoveObserver(frame);
 }
 #endif  // defined(VIDEO_HOLE)
 
 }  // namespace content