Avoid nested loops when committing updater prefs.

Fixed: 1280401
Change-Id: Ifad83da026676f339e4db8e0ebf23a1dd2bf95e2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3340087
Auto-Submit: Sorin Jianu <sorin@chromium.org>
Reviewed-by: Joshua Pawlicki <waffles@chromium.org>
Commit-Queue: Joshua Pawlicki <waffles@chromium.org>
Cr-Commit-Position: refs/heads/main@{#952103}

chrome/updater/prefs.cc

@@ -4,13 +4,16 @@
 
 #include "chrome/updater/prefs.h"
 
+#include <functional>
+#include <memory>
+#include <string>
 #include <utility>
 
 #include "base/bind.h"
 #include "base/files/file_path.h"
 #include "base/logging.h"
 #include "base/memory/ref_counted.h"
-#include "base/run_loop.h"
+#include "base/synchronization/waitable_event.h"
 #include "chrome/updater/constants.h"
 #include "chrome/updater/prefs_impl.h"
 #include "chrome/updater/updater_scope.h"
@@ -133,12 +136,14 @@ scoped_refptr<LocalPrefs> CreateLocalPrefs(UpdaterScope scope) {
 }
 
 void PrefsCommitPendingWrites(PrefService* pref_service) {
-  // Waits in the run loop until pending writes complete.
-  base::RunLoop runloop;
-  pref_service->CommitPendingWrite(base::BindOnce(
-      [](base::OnceClosure quit_closure) { std::move(quit_closure).Run(); },
-      runloop.QuitWhenIdleClosure()));
-  runloop.Run();
+  base::WaitableEvent write_complete_event;
+  pref_service->CommitPendingWrite({}, base::BindOnce(
+                                           [](base::WaitableEvent& event) {
+                                             VLOG(1) << "Prefs committed.";
+                                             event.Signal();
+                                           },
+                                           std::ref(write_complete_event)));
+  write_complete_event.Wait();
 }
 
 }  // namespace updater