Revert of Mojo: Armed Watchers

ipc/ipc_sync_channel.h

Index: ipc/ipc_sync_channel.h
diff --git a/ipc/ipc_sync_channel.h b/ipc/ipc_sync_channel.h
index 7738b7fa7cd26646128e8c852da577cf13485b98..e8c96d209adfca3ad7154d715a64cb3860a0341c 100644
--- a/ipc/ipc_sync_channel.h
+++ b/ipc/ipc_sync_channel.h
@@ -19,7 +19,7 @@
 #include "ipc/ipc_sync_message.h"
 #include "ipc/ipc_sync_message_filter.h"
 #include "mojo/public/c/system/types.h"
-#include "mojo/public/cpp/system/simple_watcher.h"
+#include "mojo/public/cpp/system/watcher.h"
 
 namespace base {
 class WaitableEvent;
@@ -27,6 +27,7 @@
 
 namespace mojo {
 class SyncHandleRegistry;
+class Watcher;
 }
 
 namespace IPC {
@@ -240,7 +241,7 @@
   scoped_refptr<mojo::SyncHandleRegistry> sync_handle_registry_;
 
   // Used to signal events between the IPC and listener threads.
-  mojo::SimpleWatcher dispatch_watcher_;
+  mojo::Watcher dispatch_watcher_;
 
   // Tracks SyncMessageFilters created before complete channel initialization.
   std::vector<scoped_refptr<SyncMessageFilter>> pre_init_sync_message_filters_;