[gnome-control-center] keyboard: Add helper to detect empty keybindings

[Bastien Nocera <hadess src gnome org>]

commit 69258a91a617175676cf4b6f29101e2afad586a0
Author: Bastien Nocera <hadess hadess net>
Date:   Thu Sep 8 14:00:07 2016 +0200

    keyboard: Add helper to detect empty keybindings
    
    We'll use this shortly.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=769314

 panels/keyboard/keyboard-shortcuts.c |   12 ++++++++++++
 panels/keyboard/keyboard-shortcuts.h |    4 ++++
 2 files changed, 16 insertions(+), 0 deletions(-)
---
diff --git a/panels/keyboard/keyboard-shortcuts.c b/panels/keyboard/keyboard-shortcuts.c
index 46e1569..91d8dfb 100644
--- a/panels/keyboard/keyboard-shortcuts.c
+++ b/panels/keyboard/keyboard-shortcuts.c
@@ -290,6 +290,18 @@ is_valid_binding (guint                  keyval,
   return TRUE;
 }
 
+gboolean
+is_empty_binding (guint                  keyval,
+                  GdkModifierType        mask,
+                  guint                  keycode)
+{
+  if (keyval == 0 &&
+      mask == 0 &&
+      keycode == 0)
+    return TRUE;
+  return FALSE;
+}
+
 gchar*
 find_free_settings_path (GSettings *settings)
 {
diff --git a/panels/keyboard/keyboard-shortcuts.h b/panels/keyboard/keyboard-shortcuts.h
index ddf8640..81e7f89 100644
--- a/panels/keyboard/keyboard-shortcuts.h
+++ b/panels/keyboard/keyboard-shortcuts.h
@@ -89,6 +89,10 @@ gboolean is_valid_binding               (guint           keyval,
                                          GdkModifierType mask,
                                          guint           keycode);
 
+gboolean is_empty_binding               (guint           keyval,
+                                         GdkModifierType mask,
+                                         guint           keycode);
+
 KeyList* parse_keylist_from_file        (const gchar *path);
 
 gchar*   convert_keysym_state_to_string (guint           keysym,