Set the WM_CLASS property of X11 windows in Linux Aura build.

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 ed64f3bdb3e443be0b3f93d105ea28a8a76aab5d..30e676288e218ca5e3a568c80ae0be17668c010b 100644
--- a/ui/views/widget/widget.h
+++ b/ui/views/widget/widget.h
@@ -216,6 +216,11 @@ class VIEWS_EXPORT Widget : public internal::NativeWidgetDelegate,
     // where it wants your window placed.) NULL is not allowed if you are using
     // aura.
     gfx::NativeView context;
+    // Only used by X11, for root level windows. Specifies the res_name and
+    // res_class fields, respectively, of the WM_CLASS window property. Controls
+    // window grouping and desktop file matching in Linux window managers.
+    std::string wm_class_name;
+    std::string wm_class_class;
   };
 
   Widget();