[mutter] theme: Update style hierarchy (again)

[Florian Müllner <fmuellner src gnome org>]

commit 4a770907c1e192d4752d71e46d6e68482f7fbead
Author: Florian Müllner <fmuellner gnome org>
Date:   Fri Nov 6 22:01:45 2015 +0100

    theme: Update style hierarchy (again)
    
    GTK+ has updated some more widgets to use element names, so do some
    catching up again ...

 src/ui/theme.c |   10 ++++------
 1 files changed, 4 insertions(+), 6 deletions(-)
---
diff --git a/src/ui/theme.c b/src/ui/theme.c
index db50007..555b902 100644
--- a/src/ui/theme.c
+++ b/src/ui/theme.c
@@ -1000,32 +1000,30 @@ meta_theme_create_style_info (GdkScreen   *screen,
     create_style_context (GTK_TYPE_HEADER_BAR,
                           style_info->styles[META_STYLE_ELEMENT_FRAME],
                           provider,
-                          NULL,
+                          "headerbar",
                           GTK_STYLE_CLASS_TITLEBAR,
                           GTK_STYLE_CLASS_HORIZONTAL,
                           "default-decoration",
-                          "header-bar",
                           NULL);
   style_info->styles[META_STYLE_ELEMENT_TITLE] =
     create_style_context (GTK_TYPE_LABEL,
                           style_info->styles[META_STYLE_ELEMENT_TITLEBAR],
                           provider,
-                          NULL,
+                          "label",
                           GTK_STYLE_CLASS_TITLE,
                           NULL);
   style_info->styles[META_STYLE_ELEMENT_BUTTON] =
     create_style_context (GTK_TYPE_BUTTON,
                           style_info->styles[META_STYLE_ELEMENT_TITLEBAR],
                           provider,
-                          NULL,
-                          GTK_STYLE_CLASS_BUTTON,
+                          "button",
                           "titlebutton",
                           NULL);
   style_info->styles[META_STYLE_ELEMENT_IMAGE] =
     create_style_context (GTK_TYPE_IMAGE,
                           style_info->styles[META_STYLE_ELEMENT_BUTTON],
                           provider,
-                          NULL,
+                          "image",
                           NULL);
   return style_info;
 }