Revert of Mojo: Armed Watchers

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 a7c1e69f607979017a29114493c51d971f7e0f2f..6743222bef081a97b80df4e89dff9289217f0a15 100644
--- a/mojo/edk/system/message_pipe_dispatcher.h
+++ b/mojo/edk/system/message_pipe_dispatcher.h
@@ -16,7 +16,6 @@
 #include "mojo/edk/system/dispatcher.h"
 #include "mojo/edk/system/message_for_transit.h"
 #include "mojo/edk/system/ports/port_ref.h"
-#include "mojo/edk/system/watcher_set.h"
 
 namespace mojo {
 namespace edk {
@@ -49,6 +48,10 @@
   // Dispatcher:
   Type GetType() const override;
   MojoResult Close() override;
+  MojoResult Watch(MojoHandleSignals signals,
+                   const Watcher::WatchCallback& callback,
+                   uintptr_t context) override;
+  MojoResult CancelWatch(uintptr_t context) override;
   MojoResult WriteMessage(std::unique_ptr<MessageForTransit> message,
                           MojoWriteMessageFlags flags) override;
   MojoResult ReadMessage(std::unique_ptr<MessageForTransit>* message,
@@ -58,10 +61,6 @@
                          MojoReadMessageFlags flags,
                          bool read_any_size) override;
   HandleSignalsState GetHandleSignalsState() const override;
-  MojoResult AddWatcherRef(const scoped_refptr<WatcherDispatcher>& watcher,
-                           uintptr_t context) override;
-  MojoResult RemoveWatcherRef(WatcherDispatcher* watcher,
-                              uintptr_t context) override;
   MojoResult AddAwakable(Awakable* awakable,
                          MojoHandleSignals signals,
                          uintptr_t context,
@@ -112,7 +111,6 @@
   bool port_transferred_ = false;
   AtomicFlag port_closed_;
   AwakableList awakables_;
-  WatcherSet watchers_;
 
   DISALLOW_COPY_AND_ASSIGN(MessagePipeDispatcher);
 };