[Background Sync] Show updated delay in Devtools.

We sometimes change the actual delay after which a periodicsync event is fired
based on other registrations for the origin. Update what we show in Devtools so
it corresponds to the actual delay_until set on the registration.

Bug: 989524, 990207
Change-Id: Ie74b5cf1c4e48d58fb1b165aec54597cc018bc71
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1733487Reviewed-by: Rayan Kanso <rayankans@chromium.org>
Commit-Queue: Mugdha Lakhani <nator@chromium.org>
Cr-Commit-Position: refs/heads/master@{#683636}

content/browser/background_sync/background_sync_manager.cc

@@ -919,7 +919,8 @@ void BackgroundSyncManager::RegisterDidGetDelay(
         DevToolsBackgroundService::kPeriodicBackgroundSync,
         /* event_name= */ "Got next event delay",
         /* instance_id= */ registration.options()->tag,
-        {{"Next Attempt Delay (ms)", GetDelayAsString(delay)}});
+        {{"Next Attempt Delay (ms)",
+          GetDelayAsString(registration.delay_until() - clock_->Now())}});
   }
 
   AddOrUpdateActiveRegistration(
@@ -1980,8 +1981,12 @@ void BackgroundSyncManager::EventCompleteDidGetDelay(
 
     std::string event_name = GetSyncEventName(registration->sync_type()) +
                              (succeeded ? " event completed" : " event failed");
+    base::TimeDelta display_delay =
+        registration->sync_type() == BackgroundSyncType::ONE_SHOT
+            ? delay
+            : registration->delay_until() - clock_->Now();
     std::map<std::string, std::string> event_metadata = {
-        {"Next Attempt Delay (ms)", GetDelayAsString(delay)}};
+        {"Next Attempt Delay (ms)", GetDelayAsString(display_delay)}};
     if (!succeeded) {
       event_metadata.emplace("Failure Reason",
                              GetEventStatusString(status_code));