Revert of Mojo: Armed Watchers

mojo/edk/js/waiting_callback.h

Index: mojo/edk/js/waiting_callback.h
diff --git a/mojo/edk/js/waiting_callback.h b/mojo/edk/js/waiting_callback.h
index f97b389aea105f84a4935b9abeef31a250e140e1..1195a985d708397a71d16720c188f852179d06db 100644
--- a/mojo/edk/js/waiting_callback.h
+++ b/mojo/edk/js/waiting_callback.h
@@ -12,7 +12,7 @@
 #include "gin/wrappable.h"
 #include "mojo/edk/js/handle.h"
 #include "mojo/public/cpp/system/core.h"
-#include "mojo/public/cpp/system/simple_watcher.h"
+#include "mojo/public/cpp/system/watcher.h"
 
 namespace mojo {
 namespace edk {
@@ -54,7 +54,7 @@
   const bool one_shot_;
 
   base::WeakPtr<gin::Runner> runner_;
-  SimpleWatcher watcher_;
+  Watcher watcher_;
   base::WeakPtrFactory<WaitingCallback> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(WaitingCallback);