marks: stub out a visualizer row

This doesn't do any rendering yet, but it gets us the plumbing we need to
start rendering mark content into a visualizer row.

lib/visualizers/sp-mark-visualizer-row.h

@@ -0,0 +1,44 @@
+/* sp-mark-visualizer-row.h
+ *
+ * Copyright 2018 Christian Hergert <chergert@redhat.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include "visualizers/sp-visualizer-row.h"
+
+G_BEGIN_DECLS
+
+#define SP_TYPE_MARK_VISUALIZER_ROW (sp_mark_visualizer_row_get_type())
+
+G_DECLARE_DERIVABLE_TYPE (SpMarkVisualizerRow, sp_mark_visualizer_row, SP, MARK_VISUALIZER_ROW, SpVisualizerRow)
+
+struct _SpMarkVisualizerRowClass
+{
+  SpVisualizerRowClass parent_class;
+
+  /*< private >*/
+  gpointer _reserved[16];
+};
+
+GtkWidget *sp_mark_visualizer_row_new      (void);
+void       sp_mark_visualizer_row_add_mark (SpMarkVisualizerRow *self,
+                                            GPid                 pid,
+                                            GPid                 tid,
+                                            const gchar         *name,
+                                            const GdkRGBA       *color);
+
+G_END_DECLS