Migrate WaitableEvent to enum-based constructor in tools/

tools/gn/input_file_manager.cc

Index: tools/gn/input_file_manager.cc
diff --git a/tools/gn/input_file_manager.cc b/tools/gn/input_file_manager.cc
index 36c0bf3c264c4444819d38f15a0aa12552d01762..c695655658dc13988c94d66ef0bbd068fe68648f 100644
--- a/tools/gn/input_file_manager.cc
+++ b/tools/gn/input_file_manager.cc
@@ -203,8 +203,11 @@ const ParseNode* InputFileManager::SyncLoadFile(
 
     if (!data->loaded) {
       // Wait for the already-pending sync load to complete.
-      if (!data->completion_event)
-        data->completion_event.reset(new base::WaitableEvent(false, false));
+      if (!data->completion_event) {
+        data->completion_event.reset(new base::WaitableEvent(
+            base::WaitableEvent::ResetPolicy::AUTOMATIC,
+            base::WaitableEvent::InitialState::NOT_SIGNALED));
+      }
       {
         base::AutoUnlock unlock(lock_);
         data->completion_event->Wait();