Remove Downcasting RVContextMenuBase in ContextMenuDeleagate implementations.

chrome/browser/ui/cocoa/renderer_context_menu/render_view_context_menu_mac.mm

Index: chrome/browser/ui/cocoa/renderer_context_menu/render_view_context_menu_mac.mm
diff --git a/chrome/browser/ui/cocoa/renderer_context_menu/render_view_context_menu_mac.mm b/chrome/browser/ui/cocoa/renderer_context_menu/render_view_context_menu_mac.mm
index 033c0addd3520806ef32bbabd7413ec64ee17f55..ace76f103f706da8f1d837c6ec79ca51e1fd32d5 100644
--- a/chrome/browser/ui/cocoa/renderer_context_menu/render_view_context_menu_mac.mm
+++ b/chrome/browser/ui/cocoa/renderer_context_menu/render_view_context_menu_mac.mm
@@ -100,10 +100,8 @@ void RenderViewContextMenuMac::Show() {
   // [NSApp currentEvent] will return a valid event.
   NSEvent* currentEvent = [NSApp currentEvent];
   NSWindow* window = [parent_view_ window];
-  NSPoint position =
-      NSMakePoint(params_.x, NSHeight([parent_view_ bounds]) - params_.y);
-  position = [parent_view_ convertPoint:position toView:nil];
   NSTimeInterval eventTime = [currentEvent timestamp];
+  NSPoint position = NSMakePoint(params_.screen_x, params_.screen_y);
   NSEvent* clickEvent = [NSEvent mouseEventWithType:NSRightMouseDown
                                            location:position
                                       modifierFlags:NSRightMouseDownMask
@@ -218,6 +216,14 @@ bool RenderViewContextMenuMac::IsCommandIdEnabled(int command_id) const {
   }
 }
 
+void RenderViewContextMenuMac::CalculateScreenCoordinatesInParams() {
+  NSPoint position =
+      NSMakePoint(params_.x, NSHeight([parent_view_ bounds]) - params_.y);
+  position = [parent_view_ convertPoint:position toView:nil];
+  params_.screen_x = position.x;
+  params_.screen_y = position.y;
+}
+
 bool RenderViewContextMenuMac::GetAcceleratorForCommandId(
     int command_id,
     ui::Accelerator* accelerator) {