--- a/dom/media/TaskQueue.cpp
+++ b/dom/media/TaskQueue.cpp
@@ -68,63 +68,16 @@ TaskQueue::DispatchLocked(already_AddRef
     NS_WARNING("Failed to dispatch runnable to run TaskQueue");
     return rv;
   }
   mIsRunning = true;
 
   return NS_OK;
 }
 
-class TaskQueueSyncRunnable : public nsRunnable {
-public:
-  explicit TaskQueueSyncRunnable(already_AddRefed<nsIRunnable> aRunnable)
-    : mRunnable(aRunnable)
-    , mMonitor("TaskQueueSyncRunnable")
-    , mDone(false)
-  {
-  }
-
-  NS_IMETHOD Run() {
-    nsresult rv = mRunnable->Run();
-    {
-      MonitorAutoLock mon(mMonitor);
-      mDone = true;
-      mon.NotifyAll();
-    }
-    return rv;
-  }
-
-  void WaitUntilDone() {
-    MonitorAutoLock mon(mMonitor);
-    while (!mDone) {
-      mon.Wait();
-    }
-  }
-private:
-  RefPtr<nsIRunnable> mRunnable;
-  Monitor mMonitor;
-  bool mDone;
-};
-
-void
-TaskQueue::SyncDispatch(already_AddRefed<nsIRunnable> aRunnable) {
-  NS_WARNING("TaskQueue::SyncDispatch is dangerous and deprecated. Stop using this!");
-  nsRefPtr<TaskQueueSyncRunnable> task(new TaskQueueSyncRunnable(Move(aRunnable)));
-
-  // Tail dispatchers don't interact nicely with sync dispatch. We require that
-  // nothing is already in the tail dispatcher, and then sidestep it for this
-  // task.
-  MOZ_ASSERT_IF(AbstractThread::GetCurrent(),
-                !AbstractThread::GetCurrent()->TailDispatcher().HasTasksFor(this));
-  nsRefPtr<TaskQueueSyncRunnable> taskRef = task;
-  Dispatch(taskRef.forget(), AssertDispatchSuccess, TailDispatch);
-
-  task->WaitUntilDone();
-}
-
 void
 TaskQueue::AwaitIdle()
 {
   MonitorAutoLock mon(mQueueMonitor);
   AwaitIdleLocked();
 }
 
 void

--- a/dom/media/TaskQueue.h
+++ b/dom/media/TaskQueue.h
@@ -44,20 +44,16 @@ public:
                 DispatchReason aReason = NormalDispatch) override
   {
     MonitorAutoLock mon(mQueueMonitor);
     nsresult rv = DispatchLocked(Move(aRunnable), AbortIfFlushing, aFailureHandling, aReason);
     MOZ_DIAGNOSTIC_ASSERT(aFailureHandling == DontAssertDispatchSuccess || NS_SUCCEEDED(rv));
     unused << rv;
   }
 
-  // DEPRECATED! Do not us, if a flush happens at the same time, this function
-  // can hang and block forever!
-  void SyncDispatch(already_AddRefed<nsIRunnable> aRunnable);
-
   // Puts the queue in a shutdown state and returns immediately. The queue will
   // remain alive at least until all the events are drained, because the Runners
   // hold a strong reference to the task queue, and one of them is always held
   // by the threadpool event queue when the task queue is non-empty.
   //
   // The returned promise is resolved when the queue goes empty.
   nsRefPtr<ShutdownPromise> BeginShutdown();