mus: Fix showing guest views in --mash and --mus.

content/browser/frame_host/render_widget_host_view_child_frame.h

Index: content/browser/frame_host/render_widget_host_view_child_frame.h
diff --git a/content/browser/frame_host/render_widget_host_view_child_frame.h b/content/browser/frame_host/render_widget_host_view_child_frame.h
index ea42f24d6df5aca81d559fd2144966f5d3a28420..244b248c0478922757d1b37ad2dd4d5d77784ebf 100644
--- a/content/browser/frame_host/render_widget_host_view_child_frame.h
+++ b/content/browser/frame_host/render_widget_host_view_child_frame.h
@@ -111,6 +111,7 @@ class CONTENT_EXPORT RenderWidgetHostViewChildFrame
   void SubmitCompositorFrame(const cc::LocalSurfaceId& local_surface_id,
                              cc::CompositorFrame frame) override;
   void OnBeginFrameDidNotSwap(const cc::BeginFrameAck& ack) override;
+  void OnSurfaceChanged(const cc::SurfaceInfo& surface_info) override;
   // Since the URL of content rendered by this class is not displayed in
   // the URL bar, this method does not need an implementation.
   void ClearCompositorFrame() override {}