RenderWidgetHostViewChildFrame's called a virtual in its ctor.

content/browser/frame_host/render_widget_host_view_child_frame.h

 // Copyright 2014 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.
 
 #ifndef CONTENT_BROWSER_FRAME_HOST_RENDER_WIDGET_HOST_VIEW_CHILD_FRAME_H_
 #define CONTENT_BROWSER_FRAME_HOST_RENDER_WIDGET_HOST_VIEW_CHILD_FRAME_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 35 matching lines @@
 // the embedding renderer process implements the platform containing the
 // widget, and the top-level frame's RenderWidgetHostView will ultimately
 // manage all native widget interaction.
 //
 // See comments in render_widget_host_view.h about this class and its members.
 class CONTENT_EXPORT RenderWidgetHostViewChildFrame
     : public RenderWidgetHostViewBase,
       public cc::SurfaceFactoryClient,
       public cc::BeginFrameObserver {
  public:
-  explicit RenderWidgetHostViewChildFrame(RenderWidgetHost* widget);
+  static RenderWidgetHostViewChildFrame* Create(RenderWidgetHost* widget);
   ~RenderWidgetHostViewChildFrame() override;
 
   void SetCrossProcessFrameConnector(
       CrossProcessFrameConnector* frame_connector);
 
   // This functions registers single-use callbacks that want to be notified when
   // the next frame is swapped. The callback is triggered by
   // OnSwapCompositorFrame, which is the appropriate time to request pixel
   // readback for the frame that is about to be drawn. Once called, the callback
   // pointer is released.
@@ skipping 122 matching lines @@
   RenderWidgetHostViewBase* GetParentView();
 
   void RegisterFrameSinkId();
   void UnregisterFrameSinkId();
 
  protected:
   friend class RenderWidgetHostView;
   friend class RenderWidgetHostViewChildFrameTest;
   friend class RenderWidgetHostViewGuestSurfaceTest;
 
+  explicit RenderWidgetHostViewChildFrame(RenderWidgetHost* widget);
+  void Init();
+
   // Clears current compositor surface, if one is in use.
   void ClearCompositorSurfaceIfNecessary();
 
   void ProcessFrameSwappedCallbacks();
 
   // The last scroll offset of the view.
   gfx::Vector2dF last_scroll_offset_;
 
   // Members will become private when RenderWidgetHostViewGuest is removed.
   // The model object.
@@ skipping 39 matching lines @@
   // The surface client ID of the parent RenderWidgetHostView.  0 if none.
   cc::FrameSinkId parent_frame_sink_id_;
 
   base::WeakPtrFactory<RenderWidgetHostViewChildFrame> weak_factory_;
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewChildFrame);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_FRAME_HOST_RENDER_WIDGET_HOST_VIEW_CHILD_FRAME_H_