Give AwakableList's wake-up method the old state in addition to the new state.

mojo/edk/system/awakable_list.h

Index: mojo/edk/system/awakable_list.h
diff --git a/mojo/edk/system/awakable_list.h b/mojo/edk/system/awakable_list.h
index 6275159987574b912e61d5ea1dfe340605626faf..7e4b732ad1c662c7bf4fa6fe8712f9063325cb8d 100644
--- a/mojo/edk/system/awakable_list.h
+++ b/mojo/edk/system/awakable_list.h
@@ -30,7 +30,8 @@ class AwakableList {
   AwakableList();
   ~AwakableList();
 
-  void AwakeForStateChange(const HandleSignalsState& state);
+  void OnStateChange(const HandleSignalsState& old_state,
+                     const HandleSignalsState& new_state);
   void CancelAll();
   void Add(Awakable* awakable, MojoHandleSignals signals, uint64_t context);
   void Remove(Awakable* awakable);