Add ContextMenuSourceType to views::ContextMenuController::ShowContextMenuForView.

ui/views/controls/button/button_dropdown.cc

Index: ui/views/controls/button/button_dropdown.cc
diff --git a/ui/views/controls/button/button_dropdown.cc b/ui/views/controls/button/button_dropdown.cc
index a243cee1917c4a0aa01e377bdf9d168218f1a012..1e659b3107b257a147f7b557552d739b95e932da 100644
--- a/ui/views/controls/button/button_dropdown.cc
+++ b/ui/views/controls/button/button_dropdown.cc
@@ -131,8 +131,10 @@ void ButtonDropDown::GetAccessibleState(ui::AccessibleViewState* state) {
   state->state = ui::AccessibilityTypes::STATE_HASPOPUP;
 }
 
-void ButtonDropDown::ShowContextMenuForView(View* source,
-                                            const gfx::Point& point) {
+void ButtonDropDown::ShowContextMenuForView(
+    View* source,
+    const gfx::Point& point,
+    ui::ContextMenuSourceType source_type) {
   if (!enabled())
     return;