Use WaitableEvents to wake up sync IPC waiting

mojo/public/cpp/bindings/lib/sync_handle_watcher.cc

Index: mojo/public/cpp/bindings/lib/sync_handle_watcher.cc
diff --git a/mojo/public/cpp/bindings/lib/sync_handle_watcher.cc b/mojo/public/cpp/bindings/lib/sync_handle_watcher.cc
index 92b91f445272f41fd6229cc391dd544bd017217c..f20af56b20a2129f40b22675d822628c50eda409 100644
--- a/mojo/public/cpp/bindings/lib/sync_handle_watcher.cc
+++ b/mojo/public/cpp/bindings/lib/sync_handle_watcher.cc
@@ -41,11 +41,11 @@ bool SyncHandleWatcher::SyncWatch(const bool* should_stop) {
     return false;
   }
 
-  // This object may be destroyed during the WatchAllHandles() call. So we have
-  // to preserve the boolean that WatchAllHandles uses.
+  // This object may be destroyed during the Wait() call. So we have to preserve
+  // the boolean that Wait uses.
   auto destroyed = destroyed_;
   const bool* should_stop_array[] = {should_stop, &destroyed->data};
-  bool result = registry_->WatchAllHandles(should_stop_array, 2);
+  bool result = registry_->Wait(should_stop_array, 2);
 
   // This object has been destroyed.
   if (destroyed->data)