[Background Sync] Fix BackgroundSyncScheduler destructor.

Stops periodic background sync timers when the scheduler is destroyed.

Change-Id: Ic1d2412df473d74206347cfafbd0fb8c0771b846
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1893882
Commit-Queue: Mugdha Lakhani <nator@chromium.org>
Commit-Queue: Rayan Kanso <rayankans@chromium.org>
Auto-Submit: Mugdha Lakhani <nator@chromium.org>
Reviewed-by: Rayan Kanso <rayankans@chromium.org>
Cr-Commit-Position: refs/heads/master@{#712099}

content/browser/background_sync/background_sync_scheduler.cc

@@ -46,7 +46,7 @@ BackgroundSyncScheduler::~BackgroundSyncScheduler() {
   for (auto& one_shot_processing_info : delayed_processing_info_one_shot_)
     one_shot_processing_info.second->Stop();
 
-  for (auto& periodic_processing_info : delayed_processing_info_one_shot_)
+  for (auto& periodic_processing_info : delayed_processing_info_periodic_)
     periodic_processing_info.second->Stop();
 }