Remove Downcasting RVContextMenuBase in ContextMenuDeleagate implementations.

chrome/browser/ui/panels/panel_extension_browsertest.cc

Index: chrome/browser/ui/panels/panel_extension_browsertest.cc
diff --git a/chrome/browser/ui/panels/panel_extension_browsertest.cc b/chrome/browser/ui/panels/panel_extension_browsertest.cc
index e56b1bea9053185436c7c1de60b6778b02ab3440..95eb5b54e5bc2b1124cb233cc99b0ebf60ee4a80 100644
--- a/chrome/browser/ui/panels/panel_extension_browsertest.cc
+++ b/chrome/browser/ui/panels/panel_extension_browsertest.cc
@@ -123,6 +123,10 @@ class PanelContextMenu : public RenderViewContextMenu {
     return menu_model_.GetIndexOfCommandId(command_id) != -1;
   }
 
+  // RenderViewContextMenuBase implementation.
+  void CalculateScreenCoordinatesInParams() override {};
+  void Show() override {}
+
  protected:
   // RenderViewContextMenu implementation.
   bool GetAcceleratorForCommandId(int command_id,