Bug 1644009 - P5. Revert "Bug 1592488 - P6. Ensure an AbstractThread exists with RemoteWorkerService thread." r=nika

DirectTask dispatching will now be directly handled by nsThread.

Differential Revision: https://phabricator.services.mozilla.com/D79089

dom/workers/remoteworkers/RemoteWorkerService.cpp

@@ -11,7 +11,6 @@
 #include "mozilla/ipc/BackgroundParent.h"
 #include "mozilla/ipc/PBackgroundChild.h"
 #include "mozilla/ipc/PBackgroundParent.h"
-#include "mozilla/AbstractThread.h"
 #include "mozilla/Services.h"
 #include "mozilla/StaticMutex.h"
 #include "mozilla/StaticPtr.h"
@@ -114,9 +113,6 @@ void RemoteWorkerService::InitializeOnTargetThread() {
   MOZ_ASSERT(mThread);
   MOZ_ASSERT(mThread->IsOnCurrentThread());
 
-  mAbstractThread = AbstractThread::CreateXPCOMThreadWrapper(
-      mThread, false /* aRequireTailDispatch */);
-
   PBackgroundChild* actorChild = BackgroundChild::GetOrCreateForCurrentThread();
   if (NS_WARN_IF(!actorChild)) {
     return;
@@ -146,7 +142,6 @@ void RemoteWorkerService::ShutdownOnTargetThread() {
   nsCOMPtr<nsIRunnable> r =
       NS_NewRunnableFunction("ShutdownOnMainThread", [self]() {
         self->mThread->Shutdown();
-        self->mAbstractThread = nullptr;
         self->mThread = nullptr;
       });
 

dom/workers/remoteworkers/RemoteWorkerService.h

@@ -13,7 +13,6 @@
 class nsIThread;
 
 namespace mozilla {
-class AbstractThread;
 namespace dom {
 
 class RemoteWorkerServiceChild;
@@ -39,10 +38,6 @@ class RemoteWorkerService final : public nsIObserver {
   void ShutdownOnTargetThread();
 
   nsCOMPtr<nsIThread> mThread;
-  // We create an AbstractThread for mThread thread so that we can use direct
-  // task dispatching with MozPromise, which is similar (but not identical to)
-  // the microtask semantics of JS promises.
-  RefPtr<AbstractThread> mAbstractThread;
   RefPtr<RemoteWorkerServiceChild> mActor;
 };