Bundle fallback ringback and busy tone audio files

Most desktop Linux sound themes lack telephony events like
phone-outgoing-calling and phone-outgoing-busy, causing gsound
playback to fail silently. Bundle OGG Vorbis fallback files and
pass GSOUND_ATTR_MEDIA_FILENAME alongside GSOUND_ATTR_EVENT_ID
so libcanberra falls back to the bundled audio when the theme
event is not found.

src/calls-media-playback.c

@@ -26,6 +26,8 @@
 
 #include "calls-media-playback.h"
 
+#include "calls-config.h"
+
 #include <gsound.h>
 
 
@@ -96,6 +98,23 @@ playback_event_to_string (PlaybackEvent event)
   }
 }
 
+
+static const char *
+playback_event_to_filename (PlaybackEvent event)
+{
+  switch (event) {
+  case PLAYBACK_CALLING:
+    return CALLS_SOUNDS_DIR "/phone-outgoing-calling.oga";
+
+  case PLAYBACK_BUSY:
+    return CALLS_SOUNDS_DIR "/phone-outgoing-busy.oga";
+
+  case PLAYBACK_LAST:
+  default:
+    return NULL;
+  }
+}
+
 static void
 calls_media_playback_dispose (GObject *object)
 {
@@ -182,11 +201,13 @@ static void
 playback_data (MediaPlaybackData *data)
 {
   const char *event_id;
+  const char *filename;
 
   g_assert (CALLS_IS_MEDIA_PLAYBACK (data->self));
   g_assert (data->self->context);
 
   event_id = playback_event_to_string (data->event);
+  filename = playback_event_to_filename (data->event);
 
   if (!event_id) {
     g_warning ("No event id found for %d", data->event);
@@ -201,6 +222,7 @@ playback_data (MediaPlaybackData *data)
                             data,
                             GSOUND_ATTR_CANBERRA_CACHE_CONTROL, "volatile",
                             GSOUND_ATTR_EVENT_ID, event_id,
+                            GSOUND_ATTR_MEDIA_FILENAME, filename,
                             NULL);
 }