background sync: Prepare for service worker UI thread core (pt 3).

This is a follow-up to r691621. It converts code added since then.

Bug: 824858
Change-Id: I6aa93cc6f5e2da40e51649c4b0052273db316581
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1786878Reviewed-by: Mugdha Lakhani <nator@chromium.org>
Commit-Queue: Matt Falkenhagen <falken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#693629}

content/browser/background_sync/background_sync_base_browsertest.cc

@@ -128,10 +128,10 @@ void BackgroundSyncBaseBrowserTest::RegistrationPendingOnCoreThread(
                           std::move(callback)));
 }
 
-void BackgroundSyncBaseBrowserTest::SetTestClockOnIOThread(
+void BackgroundSyncBaseBrowserTest::SetTestClockOnCoreThread(
     BackgroundSyncContextImpl* sync_context,
     base::SimpleTestClock* clock) {
-  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  DCHECK_CURRENTLY_ON(ServiceWorkerContext::GetCoreThreadId());
   DCHECK(clock);
 
   BackgroundSyncManager* background_sync_manager =
@@ -205,19 +205,24 @@ bool BackgroundSyncBaseBrowserTest::RunScript(const std::string& script,
 }
 
 void BackgroundSyncBaseBrowserTest::SetTestClock(base::SimpleTestClock* clock) {
-  base::RunLoop run_loop;
-
   StoragePartitionImpl* storage = GetStorage();
   BackgroundSyncContextImpl* sync_context = storage->GetBackgroundSyncContext();
 
+  // TODO(crbug.com/824858): Remove the else branch after the feature is
+  // enabled. Also, try to make a RunOrPostTaskOnThreadAndReply() function so
+  // the if/else isn't needed.
+  if (ServiceWorkerContext::IsServiceWorkerOnUIEnabled()) {
+    SetTestClockOnCoreThread(sync_context, clock);
+  } else {
+    base::RunLoop run_loop;
     base::PostTaskWithTraitsAndReply(
-      FROM_HERE, {BrowserThread::IO},
-      base::BindOnce(&BackgroundSyncBaseBrowserTest::SetTestClockOnIOThread,
+        FROM_HERE, ServiceWorkerContext::GetCoreThreadId(),
+        base::BindOnce(&BackgroundSyncBaseBrowserTest::SetTestClockOnCoreThread,
                        base::Unretained(this), base::Unretained(sync_context),
                        clock),
         run_loop.QuitClosure());
-
     run_loop.Run();
+  }
 }
 
 void BackgroundSyncBaseBrowserTest::ClearStoragePartitionData() {

content/browser/background_sync/background_sync_base_browsertest.h

@@ -99,7 +99,7 @@ class BackgroundSyncBaseBrowserTest : public ContentBrowserTest {
       const GURL& url,
       base::OnceCallback<void(bool)> callback);
   StoragePartitionImpl* GetStorage();
-  void SetTestClockOnIOThread(BackgroundSyncContextImpl* sync_context,
+  void SetTestClockOnCoreThread(BackgroundSyncContextImpl* sync_context,
                                 base::SimpleTestClock* clock);
 
   Shell* shell_ = nullptr;