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

mojo/edk/system/local_message_pipe_endpoint.h

Index: mojo/edk/system/local_message_pipe_endpoint.h
diff --git a/mojo/edk/system/local_message_pipe_endpoint.h b/mojo/edk/system/local_message_pipe_endpoint.h
index 7e9904c35a01873384afb9dffa281f95d9432318..dc2aeeb8c1d7c53d50223123394d1f7c66e2c4d1 100644
--- a/mojo/edk/system/local_message_pipe_endpoint.h
+++ b/mojo/edk/system/local_message_pipe_endpoint.h
@@ -38,15 +38,14 @@ class LocalMessagePipeEndpoint final : public MessagePipeEndpoint {
                          MojoReadMessageFlags flags) override;
   HandleSignalsState GetHandleSignalsState() const override;
   MojoResult AddAwakable(Awakable* awakable,
-                         MojoHandleSignals signals,
-                         bool force,
                          uint64_t context,
+                         bool force,
+                         MojoHandleSignals signals,
                          HandleSignalsState* signals_state) override;
-  void RemoveAwakable(Awakable* awakable,
+  void RemoveAwakable(bool match_context,
+                      Awakable* awakable,
+                      uint64_t context,
                       HandleSignalsState* signals_state) override;
-  void RemoveAwakableWithContext(Awakable* awakable,
-                                 uint64_t context,
-                                 HandleSignalsState* signals_state) override;
 
   // This is only to be used by |MessagePipe|:
   MessageInTransitQueue* message_queue() { return &message_queue_; }