views: provide feedback when editing fails

ui/views/style/platform_style_mac.mm

Index: ui/views/style/platform_style_mac.mm
diff --git a/ui/views/style/platform_style_mac.mm b/ui/views/style/platform_style_mac.mm
index 5381c80e67f97bbe0ff9a71df7537347cd550583..8cc98004f6ce3dcd5019c7379b611e0cc968b32d 100644
--- a/ui/views/style/platform_style_mac.mm
+++ b/ui/views/style/platform_style_mac.mm
@@ -17,6 +17,8 @@
 #include "ui/views/style/mac/combobox_background_mac.h"
 #include "ui/views/style/mac/dialog_button_border_mac.h"
 
+#import <Cocoa/Cocoa.h>
+
 namespace views {
 
 const int PlatformStyle::kComboboxNormalArrowPadding = 0;
@@ -96,4 +98,9 @@ void PlatformStyle::ApplyLabelButtonTextStyle(
       theme->GetSystemColor(ui::NativeTheme::kColorId_ButtonHighlightColor);
 }
 
+// static
+void PlatformStyle::OnTextfieldKeypressUnhandled() {
+  NSBeep();
+}
+
 }  // namespace views