Fix context menu positioning in MimeHandlerViewGuest.

extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest.h

Index: extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest.h
diff --git a/extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest.h b/extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest.h
index d788cb540d92895692a1ab0a14f25597d1ce5108..f678d4eb60bf0961a06a24832349be014b6990df 100644
--- a/extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest.h
+++ b/extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest.h
@@ -10,6 +10,7 @@
 
 namespace content {
 class WebContents;
+struct ContextMenuParams;
 }  // namespace content
 
 namespace extensions {
@@ -47,6 +48,7 @@ class MimeHandlerViewGuest : public GuestView<MimeHandlerViewGuest>,
 
   // WebContentsDelegate implementation.
   void ContentsZoomChange(bool zoom_in) override;
+  bool HandleContextMenu(const content::ContextMenuParams& params) override;
   void HandleKeyboardEvent(
       content::WebContents* source,
       const content::NativeWebKeyboardEvent& event) override;