Allow MimeHandlerViewGuest be embedded inside OOPIFs

content/browser/renderer_host/render_widget_host_view_base.h

Index: content/browser/renderer_host/render_widget_host_view_base.h
diff --git a/content/browser/renderer_host/render_widget_host_view_base.h b/content/browser/renderer_host/render_widget_host_view_base.h
index ce60e771273c9431ac86f9af584a7366e53c6b00..001376961177c6019a303a4efc812a432b0e1c75 100644
--- a/content/browser/renderer_host/render_widget_host_view_base.h
+++ b/content/browser/renderer_host/render_widget_host_view_base.h
@@ -287,6 +287,13 @@ class CONTENT_EXPORT RenderWidgetHostViewBase : public RenderWidgetHostView,
   // need to also be resolved.
   virtual bool IsRenderWidgetHostViewChildFrame();
 
+  // TODO(ekaramad): This is used for input event routing when the target of
+  // events is a RenderWidgetHostViewGuest which is embeded in an OOPIF (the
+  // only example right now is MimeHandlerViewGuest). Same as above, this
+  // method should be removed when either direct routing is supported for
+  // RWHVG or RWHVG is removed entirely (https://crbug.com/533069).
+  virtual RenderWidgetHostViewBase* GetOuterView();
+
   //----------------------------------------------------------------------------
   // The following methods are related to IME.
   // TODO(ekaramad): Most of the IME methods should not stay virtual after IME