Migrate WaitableEvent to enum-based constructor in services/

services/shell/runner/host/child_process_base.cc

Index: services/shell/runner/host/child_process_base.cc
diff --git a/services/shell/runner/host/child_process_base.cc b/services/shell/runner/host/child_process_base.cc
index 3778b0f1c1a1ffe2e19e015905036f1fc6de780d..eb798f3d788dcfd594a01e3b0428cb132323db13 100644
--- a/services/shell/runner/host/child_process_base.cc
+++ b/services/shell/runner/host/child_process_base.cc
@@ -62,7 +62,10 @@ std::unique_ptr<LinuxSandbox> InitializeSandbox() {
 class ScopedAppContext : public mojo::edk::ProcessDelegate {
  public:
   ScopedAppContext()
-      : io_thread_("io_thread"), wait_for_shutdown_event_(true, false) {
+      : io_thread_("io_thread"),
+        wait_for_shutdown_event_(
+            base::WaitableEvent::ResetPolicy::MANUAL,
+            base::WaitableEvent::InitialState::NOT_SIGNALED) {
     // Initialize Mojo before starting any threads.
     mojo::edk::Init();