Do not use the default GMainContext

Using the default GMainContext may cause deadlocks when mpv-mpris is
loaded in an mpv frontend that use GLib.

mpris.c

@@ -988,15 +988,17 @@ static void wakeup_handler(void *fd)
 // Plugin entry point
 int mpv_open_cplugin(mpv_handle *mpv)
 {
+    GMainContext *ctx;
     GMainLoop *loop;
     UserData ud = {0};
     GError *error = NULL;
     GDBusNodeInfo *introspection_data = NULL;
     int pipe[2];
-    guint mpv_pipe_source;
-    guint timeout_source;
+    GSource *mpv_pipe_source;
+    GSource *timeout_source;
 
-    loop = g_main_loop_new(NULL, FALSE);
+    ctx = g_main_context_new();
+    loop = g_main_loop_new(ctx, FALSE);
 
     // Load introspection data and split into separate interfaces
     introspection_data = g_dbus_node_info_new_for_xml(introspection_xml, &error);
@@ -1015,13 +1017,15 @@ int mpv_open_cplugin(mpv_handle *mpv)
     ud.changed_properties = g_hash_table_new(g_str_hash, g_str_equal);
     ud.seek_expected = FALSE;
 
+    g_main_context_push_thread_default(ctx);
     ud.bus_id = g_bus_own_name(G_BUS_TYPE_SESSION,
                                "org.mpris.MediaPlayer2.mpv",
                                G_BUS_NAME_OWNER_FLAGS_DO_NOT_QUEUE,
                                on_bus_acquired,
                                NULL,
                                on_name_lost,
                                &ud, NULL);
+    g_main_context_pop_thread_default(ctx);
 
     // Receive event for property changes
     mpv_observe_property(mpv, 0, "pause", MPV_FORMAT_FLAG);
@@ -1040,21 +1044,32 @@ int mpv_open_cplugin(mpv_handle *mpv)
     }
     fcntl(pipe[0], F_SETFL, O_NONBLOCK);
     mpv_set_wakeup_callback(mpv, wakeup_handler, &pipe[1]);
-    mpv_pipe_source = g_unix_fd_add(pipe[0], G_IO_IN, event_handler, &ud);
+    mpv_pipe_source = g_unix_fd_source_new(pipe[0], G_IO_IN);
+    g_source_set_callback(mpv_pipe_source,
+                          G_SOURCE_FUNC(event_handler),
+                          &ud,
+                          NULL);
+    g_source_attach(mpv_pipe_source, ctx);
 
     // Emit any new property changes every 100ms
-    timeout_source = g_timeout_add(100, emit_property_changes, &ud);
+    timeout_source = g_timeout_source_new(100);
+    g_source_set_callback(timeout_source,
+                          G_SOURCE_FUNC(emit_property_changes),
+                          &ud,
+                          NULL);
+    g_source_attach(timeout_source, ctx);
 
     g_main_loop_run(loop);
 
-    g_source_remove(mpv_pipe_source);
-    g_source_remove(timeout_source);
+    g_source_unref(mpv_pipe_source);
+    g_source_unref(timeout_source);
 
     g_dbus_connection_unregister_object(ud.connection, ud.root_interface_id);
     g_dbus_connection_unregister_object(ud.connection, ud.player_interface_id);
 
     g_bus_unown_name(ud.bus_id);
     g_main_loop_unref(loop);
+    g_main_context_unref(ctx);
     g_dbus_node_info_unref(introspection_data);
 
     return 0;