Bug 1734700 - Use the IO event queue for IOUtils background tasks, r=KrisWright

Differential Revision: https://phabricator.services.mozilla.com/D128311

dom/system/IOUtils.cpp

@@ -1597,14 +1597,20 @@ template <typename OkT, typename Fn>
 RefPtr<IOUtils::IOPromise<OkT>> IOUtils::EventQueue::Dispatch(Fn aFunc) {
   MOZ_RELEASE_ASSERT(mBackgroundEventTarget);
 
-  return InvokeAsync(
-      mBackgroundEventTarget, __func__, [func = std::move(aFunc)]() {
-        Result<OkT, IOError> result = func();
-        if (result.isErr()) {
-          return IOPromise<OkT>::CreateAndReject(result.unwrapErr(), __func__);
-        }
-        return IOPromise<OkT>::CreateAndResolve(result.unwrap(), __func__);
-      });
+  auto promise =
+      MakeRefPtr<typename IOUtils::IOPromise<OkT>::Private>(__func__);
+  mBackgroundEventTarget->Dispatch(
+      NS_NewRunnableFunction("IOUtils::EventQueue::Dispatch",
+                             [promise, func = std::move(aFunc)] {
+                               Result<OkT, IOError> result = func();
+                               if (result.isErr()) {
+                                 promise->Reject(result.unwrapErr(), __func__);
+                               } else {
+                                 promise->Resolve(result.unwrap(), __func__);
+                               }
+                             }),
+      NS_DISPATCH_EVENT_MAY_BLOCK);
+  return promise;
 };
 
 Result<already_AddRefed<nsIAsyncShutdownClient>, nsresult>

tools/profiler/tests/xpcshell/test_feature_fileioall.js

@@ -14,7 +14,7 @@ add_task(async () => {
   const filename = "test_marker_fileio";
   const profile = await startProfilerAndTriggerFileIO({
     features: ["fileioall"],
-    threadsFilter: ["GeckoMain", "BackgroundThreadPool"],
+    threadsFilter: ["GeckoMain", "BgIOThreadPool"],
     filename,
   });
 
@@ -25,7 +25,7 @@ add_task(async () => {
   let backgroundThreadFileIO;
   for (const thread of threads) {
     // Check for FileIO in any of the background threads.
-    if (thread.name.startsWith("BackgroundThreadPool")) {
+    if (thread.name.startsWith("BgIOThreadPool")) {
       const markers = getInflatedFileIOMarkers(thread, filename);
       if (markers.length > 0) {
         backgroundThread = thread;