[gnome-photos] pipeline: Add a missing const to an input string parameter

[Debarshi Ray <debarshir src gnome org>]

commit 2962a6c8fc58e5466e0215a68e4d0896668ebc30
Author: Debarshi Ray <debarshir gnome org>
Date:   Tue Aug 9 10:22:44 2016 +0200

    pipeline: Add a missing const to an input string parameter

 src/photos-pipeline.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/photos-pipeline.c b/src/photos-pipeline.c
index 871b1b1..6ad2cdd 100644
--- a/src/photos-pipeline.c
+++ b/src/photos-pipeline.c
@@ -86,7 +86,7 @@ photos_pipeline_reset (PhotosPipeline *self)
 
 
 static gboolean
-photos_pipeline_create_graph_from_xml (PhotosPipeline *self, gchar *contents)
+photos_pipeline_create_graph_from_xml (PhotosPipeline *self, const gchar *contents)
 {
   GeglNode *graph = NULL;
   GeglNode *input;