[Mac] Pressing unsupported key should not generate keyevents

content/browser/renderer_host/render_widget_host_view_mac.mm

Index: content/browser/renderer_host/render_widget_host_view_mac.mm
diff --git a/content/browser/renderer_host/render_widget_host_view_mac.mm b/content/browser/renderer_host/render_widget_host_view_mac.mm
index 1c9ce1e430de8821450808b9dd533f7c5999f680..a1f526ab8b5002623409212db423728fe3f751b5 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.mm
+++ b/content/browser/renderer_host/render_widget_host_view_mac.mm
@@ -2112,8 +2112,10 @@ void RenderWidgetHostViewMac::OnDisplayMetricsChanged(
   if ([theEvent type] == NSFlagsChanged) {
     // Ignore NSFlagsChanged events from the NumLock and Fn keys as
     // Safari does in -[WebHTMLView flagsChanged:] (of "WebHTMLView.mm").
+    // Also ignore unsupported |keyCode| (255) generated by Convert, NonConvert
+    // and KanaMode from JIS PC keyboard.
     int keyCode = [theEvent keyCode];
-    if (!keyCode || keyCode == 10 || keyCode == 63)
+    if (!keyCode || keyCode == 10 || keyCode == 63 || keyCode == 255)
       return;
   }