[gnome-photos] base-item: Add a create_filename_fallback pure virtual method

[Debarshi Ray <debarshir src gnome org>]

commit 55e8444f69fe1d261e279091b317501ae97c3dc9
Author: Debarshi Ray <debarshir gnome org>
Date:   Fri Jun 24 12:08:34 2016 +0200

    base-item: Add a create_filename_fallback pure virtual method
    
    Sometimes we need a filename for a BaseItem, even if it is not a
    LocalItem:
     - to represent the final outcome of an export
     - when caching
    
    Different BaseItem sub-classes can implement this virtual method to
    create a string that can be used as a filename in the absence of an
    nfo:fileName entry in the database.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=766162

 src/photos-base-item.h |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/src/photos-base-item.h b/src/photos-base-item.h
index 9585a90..eab854c 100644
--- a/src/photos-base-item.h
+++ b/src/photos-base-item.h
@@ -74,6 +74,7 @@ struct _PhotosBaseItemClass
   const gchar *miner_object_path;
 
   /* virtual methods */
+  gchar      *(*create_filename_fallback)   (PhotosBaseItem *self);
   gchar      *(*create_name_fallback)       (PhotosBaseItem *self);
   gchar      *(*create_pipeline_path)       (PhotosBaseItem *self);
   gboolean    (*create_thumbnail)           (PhotosBaseItem *self, GCancellable *cancellable, GError 
**error);