Keystore 2.0: Add shelf to async tasks.

The Shelf allows async tasks to store state across invocations.

Test: N/A
Change-Id: Ic4cbf7973e0c812479da87431372ed210e9411cf
diff --git a/keystore2/src/gc.rs b/keystore2/src/gc.rs
index fbb1cf6..718fe77 100644
--- a/keystore2/src/gc.rs
+++ b/keystore2/src/gc.rs
@@ -82,7 +82,7 @@
             }
         }
         if self.remaining_tries != 0 {
-            ASYNC_TASK.queue_lo(move || {
+            ASYNC_TASK.queue_lo(move |_| {
                 self.process_all();
             })
         }
@@ -92,6 +92,6 @@
     /// their deletion. We only process one key at a time and then schedule another
     /// attempt by queueing it in the async_task (low priority) queue.
     pub fn notify_gc() {
-        ASYNC_TASK.queue_lo(|| Self { remaining_tries: Self::MAX_ERROR_RETRIES }.process_all())
+        ASYNC_TASK.queue_lo(|_| Self { remaining_tries: Self::MAX_ERROR_RETRIES }.process_all())
     }
 }