Rationalize AddAwakable...() and RemoveAwakable...() methods.

mojo/edk/system/message_pipe_dispatcher.h

Index: mojo/edk/system/message_pipe_dispatcher.h
diff --git a/mojo/edk/system/message_pipe_dispatcher.h b/mojo/edk/system/message_pipe_dispatcher.h
index a7360a6da6b9f32af3b2769ff55ccf7c1eb37a5b..4f5c543b1894b090c0bef841a2ccdbf59ac43e2f 100644
--- a/mojo/edk/system/message_pipe_dispatcher.h
+++ b/mojo/edk/system/message_pipe_dispatcher.h
@@ -97,16 +97,14 @@ class MessagePipeDispatcher final : public Dispatcher {
                                    MojoReadMessageFlags flags) override;
   HandleSignalsState GetHandleSignalsStateImplNoLock() const override;
   MojoResult AddAwakableImplNoLock(Awakable* awakable,
-                                   MojoHandleSignals signals,
-                                   bool force,
                                    uint64_t context,
+                                   bool force,
+                                   MojoHandleSignals signals,
                                    HandleSignalsState* signals_state) override;
-  void RemoveAwakableImplNoLock(Awakable* awakable,
+  void RemoveAwakableImplNoLock(bool match_context,
+                                Awakable* awakable,
+                                uint64_t context,
                                 HandleSignalsState* signals_state) override;
-  void RemoveAwakableWithContextImplNoLock(
-      Awakable* awakable,
-      uint64_t context,
-      HandleSignalsState* signals_state) override;
   void StartSerializeImplNoLock(Channel* channel,
                                 size_t* max_size,
                                 size_t* max_platform_handles) override