application: Remove gcal_application_get_clock()

That moved to GcalContext, and now that all pieces who
used it have access to the context, we can just use it.

src/views/gcal-week-header.c

@@ -1669,8 +1669,6 @@ gcal_week_header_class_init (GcalWeekHeaderClass *kclass)
 static void
 gcal_week_header_init (GcalWeekHeader *self)
 {
-  GcalApplication *application;
-
   self->expanded = FALSE;
   self->selection_start = -1;
   self->selection_end = -1;
@@ -1690,17 +1688,6 @@ G_GNUC_END_IGNORE_DEPRECATIONS
                      NULL,
                      0,
                      GDK_ACTION_MOVE);
-
-  /* Connect to the wall clock */
-  application = GCAL_APPLICATION (g_application_get_default ());
-
-  g_assert (application != NULL);
-
-  g_signal_connect_object (gcal_application_get_clock (application),
-                           "day-changed",
-                           G_CALLBACK (gtk_widget_queue_draw),
-                           self,
-                           G_CONNECT_SWAPPED);
 }
 
 /* Private API */
@@ -1831,6 +1818,12 @@ gcal_week_header_set_context (GcalWeekHeader *self,
   g_return_if_fail (GCAL_IS_WEEK_HEADER (self));
 
   self->context = context;
+
+  g_signal_connect_object (gcal_context_get_clock (context),
+                           "day-changed",
+                           G_CALLBACK (gtk_widget_queue_draw),
+                           self,
+                           G_CONNECT_SWAPPED);
 }
 
 void