[grilo] Use GRL_METADATA_KEY_INVALID instead of NULL.

[Juan A. Suarez Romero <jasuarez src gnome org>]

commit a6baa038b4ab344f3c9768f251d6865197ddd9b9
Author: Murray Cumming <murrayc openismus com>
Date:   Tue Oct 2 12:35:16 2012 +0200

    Use GRL_METADATA_KEY_INVALID instead of NULL.
    
    This is what the grl_metadata_key_list_new() documentation
    says we should do. NULL is the same thing, but that is an internal
    detail.
    
    This fixes https://bugzilla.gnome.org/show_bug.cgi?id=685274
    
    Signed-off-by: Juan A. Suarez Romero <jasuarez igalia com>

 doc/grilo/plugins-sources.xml            |    2 +-
 examples/browsing.c                      |    2 +-
 examples/efficient-metadata-resolution.c |    4 ++--
 examples/multivalues.c                   |    2 +-
 examples/searching.c                     |    2 +-
 5 files changed, 6 insertions(+), 6 deletions(-)
---
diff --git a/doc/grilo/plugins-sources.xml b/doc/grilo/plugins-sources.xml
index 41be993..da7d33d 100644
--- a/doc/grilo/plugins-sources.xml
+++ b/doc/grilo/plugins-sources.xml
@@ -298,7 +298,7 @@ grl_foo_source_supported_keys (GrlSource *source)
                                       GRL_METADATA_KEY_MIME,
                                       GRL_METADATA_KEY_ARTIST,
                                       GRL_METADATA_KEY_DURATION,
-                                      NULL);
+                                      GRL_METADATA_KEY_INVALID);
   }
   return keys;
 }
diff --git a/examples/browsing.c b/examples/browsing.c
index 6c59a86..d05282a 100644
--- a/examples/browsing.c
+++ b/examples/browsing.c
@@ -69,7 +69,7 @@ source_added_cb (GrlRegistry *registry, GrlSource *source, gpointer user_data)
 					    GRL_METADATA_KEY_DURATION,
 					    GRL_METADATA_KEY_URL,
 					    GRL_METADATA_KEY_CHILDCOUNT,
-					    NULL);
+					    GRL_METADATA_KEY_INVALID);
   g_debug ("Detected new source available: '%s'",
            grl_source_get_name (source));
 
diff --git a/examples/efficient-metadata-resolution.c b/examples/efficient-metadata-resolution.c
index c99b037..3b3ee72 100644
--- a/examples/efficient-metadata-resolution.c
+++ b/examples/efficient-metadata-resolution.c
@@ -57,7 +57,7 @@ search_cb (GrlSource *source,
     g_debug ("URL no available, trying with slow keys now");
     GrlOperationOptions *options;
     GrlCaps *caps;
-    GList *keys = grl_metadata_key_list_new (GRL_METADATA_KEY_URL, NULL);
+    GList *keys = grl_metadata_key_list_new (GRL_METADATA_KEY_URL, GRL_METADATA_KEY_INVALID);
 
     caps = grl_source_get_caps (source, GRL_OP_RESOLVE);
     options = grl_operation_options_new (caps);
@@ -87,7 +87,7 @@ source_added_cb (GrlRegistry *registry, GrlSource *source, gpointer user_data)
 
   GList *keys = grl_metadata_key_list_new (GRL_METADATA_KEY_TITLE,
 					   GRL_METADATA_KEY_URL,
-					   NULL);
+					   GRL_METADATA_KEY_INVALID);
 
   /* The source must be searchable */
   if (!(grl_source_supported_operations (source) & GRL_OP_SEARCH))
diff --git a/examples/multivalues.c b/examples/multivalues.c
index c31a54c..b492849 100644
--- a/examples/multivalues.c
+++ b/examples/multivalues.c
@@ -56,7 +56,7 @@ source_added_cb (GrlRegistry *registry, GrlSource *source, gpointer user_data)
   GList * keys = grl_metadata_key_list_new (GRL_METADATA_KEY_TITLE,
 					    GRL_METADATA_KEY_URL,
                                             GRL_METADATA_KEY_MIME,
-					    NULL);
+					    GRL_METADATA_KEY_INVALID);
 
   /* Not interested if not searchable */
   if (!(grl_source_supported_operations (source) & GRL_OP_SEARCH))
diff --git a/examples/searching.c b/examples/searching.c
index 0779660..c8eea3d 100644
--- a/examples/searching.c
+++ b/examples/searching.c
@@ -53,7 +53,7 @@ source_added_cb (GrlRegistry *registry, GrlSource *source, gpointer user_data)
   GList * keys = grl_metadata_key_list_new (GRL_METADATA_KEY_TITLE,
 					    GRL_METADATA_KEY_DURATION,
 					    GRL_METADATA_KEY_CHILDCOUNT,
-					    NULL);
+					    GRL_METADATA_KEY_INVALID);
 
   /* Not interested if not searchable */
   if (!(grl_source_supported_operations (source) & GRL_OP_SEARCH))