views: Packaged app window icon should be system/generic icon, if icon is not set by default.

ui/views/widget/widget.h

Index: ui/views/widget/widget.h
diff --git a/ui/views/widget/widget.h b/ui/views/widget/widget.h
index 95e0d540adf4d6d352300b383e4c762ab10e2841..f9d5b67c46a8e6e8d88ef0ebc188e640d3afb2f9 100644
--- a/ui/views/widget/widget.h
+++ b/ui/views/widget/widget.h
@@ -164,6 +164,9 @@ class VIEWS_EXPORT Widget : public internal::NativeWidgetDelegate,
     // and icon should not be rendered, and that the client area should be
     // equivalent to the window area.
     bool remove_standard_frame;
+    // Only used by ShellWindow on Windows. Specifies that the default icon of
+    // packaged app should be the system default icon.
+    bool use_system_default_icon;
     // Whether the widget should be maximized or minimized.
     ui::WindowShowState show_state;
     // Should the widget be double buffered? Default is false.