diff --git a/dom/base/DOMPrefsInternal.h b/dom/base/DOMPrefsInternal.h
index 463babfc2ef6..94d6a1073141 100644
--- a/dom/base/DOMPrefsInternal.h
+++ b/dom/base/DOMPrefsInternal.h
@@ -39,6 +39,7 @@ DOM_PREF(NetworkInformationEnabled, "dom.netinfo.enabled")
 DOM_PREF(FetchObserverEnabled, "dom.fetchObserver.enabled")
 DOM_PREF(ResistFingerprintingEnabled, "privacy.resistFingerprinting")
 DOM_PREF(DevToolsEnabled, "devtools.enabled")
+DOM_PREF(PerformanceObserverEnabled, "dom.enable_performance_observer")
 
 DOM_WEBIDL_PREF(ImageBitmapExtensionsEnabled)
 DOM_WEBIDL_PREF(DOMCachesEnabled)
@@ -54,3 +55,4 @@ DOM_WEBIDL_PREF(OffscreenCanvasEnabled)
 DOM_WEBIDL_PREF(WebkitBlinkDirectoryPickerEnabled)
 DOM_WEBIDL_PREF(NetworkInformationEnabled)
 DOM_WEBIDL_PREF(FetchObserverEnabled)
+DOM_WEBIDL_PREF(PerformanceObserverEnabled)
diff --git a/dom/performance/Performance.cpp b/dom/performance/Performance.cpp
index 3b35967ce62f..c241123adbcf 100644
--- a/dom/performance/Performance.cpp
+++ b/dom/performance/Performance.cpp
@@ -36,38 +36,6 @@
 namespace mozilla {
 namespace dom {
 
-namespace {
-
-class PrefEnabledRunnable final
-  : public WorkerCheckAPIExposureOnMainThreadRunnable
-{
-public:
-  PrefEnabledRunnable(WorkerPrivate* aWorkerPrivate,
-                      const nsCString& aPrefName)
-    : WorkerCheckAPIExposureOnMainThreadRunnable(aWorkerPrivate)
-    , mEnabled(false)
-    , mPrefName(aPrefName)
-  { }
-
-  bool MainThreadRun() override
-  {
-    MOZ_ASSERT(NS_IsMainThread());
-    mEnabled = Preferences::GetBool(mPrefName.get(), false);
-    return true;
-  }
-
-  bool IsEnabled() const
-  {
-    return mEnabled;
-  }
-
-private:
-  bool mEnabled;
-  nsCString mPrefName;
-};
-
-} // anonymous namespace
-
 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(Performance)
 NS_INTERFACE_MAP_END_INHERITING(DOMEventTargetHelper)
 
@@ -539,24 +507,6 @@ Performance::QueueEntry(PerformanceEntry* aEntry)
   }
 }
 
-/* static */ bool
-Performance::IsObserverEnabled(JSContext* aCx, JSObject* aGlobal)
-{
-  if (NS_IsMainThread()) {
-    return Preferences::GetBool("dom.enable_performance_observer", false);
-  }
-
-  WorkerPrivate* workerPrivate = GetCurrentThreadWorkerPrivate();
-  MOZ_ASSERT(workerPrivate);
-  workerPrivate->AssertIsOnWorkerThread();
-
-  RefPtr<PrefEnabledRunnable> runnable =
-    new PrefEnabledRunnable(workerPrivate,
-                            NS_LITERAL_CSTRING("dom.enable_performance_observer"));
-
-  return runnable->Dispatch() && runnable->IsEnabled();
-}
-
 void
 Performance::MemoryPressure()
 {
diff --git a/dom/performance/Performance.h b/dom/performance/Performance.h
index 0bfe0d434195..2a529bd4a85e 100644
--- a/dom/performance/Performance.h
+++ b/dom/performance/Performance.h
@@ -9,6 +9,7 @@
 
 #include "mozilla/Attributes.h"
 #include "mozilla/DOMEventTargetHelper.h"
+#include "mozilla/dom/DOMPrefs.h"
 #include "nsCOMPtr.h"
 #include "nsDOMNavigationTiming.h"
 
diff --git a/dom/performance/PerformanceObserverEntryList.h b/dom/performance/PerformanceObserverEntryList.h
index e78ce7dfb326..e693b5522802 100644
--- a/dom/performance/PerformanceObserverEntryList.h
+++ b/dom/performance/PerformanceObserverEntryList.h
@@ -11,6 +11,7 @@
 #include "nsISupports.h"
 #include "nsTArray.h"
 #include "nsWrapperCache.h"
+#include "mozilla/dom/DOMPrefs.h"
 #include "mozilla/dom/PerformanceEntryBinding.h"
 
 namespace mozilla {
diff --git a/dom/webidl/PerformanceObserver.webidl b/dom/webidl/PerformanceObserver.webidl
index e275904e8693..7e6f370de017 100644
--- a/dom/webidl/PerformanceObserver.webidl
+++ b/dom/webidl/PerformanceObserver.webidl
@@ -15,7 +15,7 @@ dictionary PerformanceObserverInit {
 callback PerformanceObserverCallback = void (PerformanceObserverEntryList entries,
                                              PerformanceObserver observer);
 
-[Func="Performance::IsObserverEnabled",
+[Func="mozilla::dom::DOMPrefs::PerformanceObserverEnabled",
  Constructor(PerformanceObserverCallback callback),
  Exposed=(Window,Worker)]
 interface PerformanceObserver {
diff --git a/dom/webidl/PerformanceObserverEntryList.webidl b/dom/webidl/PerformanceObserverEntryList.webidl
index cff4ee1b034a..e944535d233a 100644
--- a/dom/webidl/PerformanceObserverEntryList.webidl
+++ b/dom/webidl/PerformanceObserverEntryList.webidl
@@ -14,7 +14,8 @@ dictionary PerformanceEntryFilterOptions {
   DOMString initiatorType;
 };
 
-[Func="Performance::IsObserverEnabled", Exposed=(Window,Worker)]
+[Func="mozilla::dom::DOMPrefs::PerformanceObserverEnabled",
+ Exposed=(Window,Worker)]
 interface PerformanceObserverEntryList {
   PerformanceEntryList getEntries(optional PerformanceEntryFilterOptions filter);
   PerformanceEntryList getEntriesByType(DOMString entryType);
diff --git a/dom/workers/WorkerRunnable.cpp b/dom/workers/WorkerRunnable.cpp
index e14222e52e5b..17638b8228ae 100644
--- a/dom/workers/WorkerRunnable.cpp
+++ b/dom/workers/WorkerRunnable.cpp
@@ -626,24 +626,6 @@ WorkerMainThreadRunnable::Run()
   return NS_OK;
 }
 
-WorkerCheckAPIExposureOnMainThreadRunnable::WorkerCheckAPIExposureOnMainThreadRunnable(WorkerPrivate* aWorkerPrivate):
-  WorkerMainThreadRunnable(aWorkerPrivate,
-                           NS_LITERAL_CSTRING("WorkerCheckAPIExposureOnMainThread"))
-{}
-
-WorkerCheckAPIExposureOnMainThreadRunnable::~WorkerCheckAPIExposureOnMainThreadRunnable()
-{}
-
-bool
-WorkerCheckAPIExposureOnMainThreadRunnable::Dispatch()
-{
-  ErrorResult rv;
-  WorkerMainThreadRunnable::Dispatch(Terminating, rv);
-  bool ok = !rv.Failed();
-  rv.SuppressException();
-  return ok;
-}
-
 bool
 WorkerSameThreadRunnable::PreDispatch(WorkerPrivate* aWorkerPrivate)
 {
diff --git a/dom/workers/WorkerRunnable.h b/dom/workers/WorkerRunnable.h
index 29b570e29683..ae571e269bcf 100644
--- a/dom/workers/WorkerRunnable.h
+++ b/dom/workers/WorkerRunnable.h
@@ -457,27 +457,6 @@ protected:
   UniquePtr<WorkerHolder> mWorkerHolder;
 };
 
-// Class for checking API exposure.  This totally violates the "MUST" in the
-// comments on WorkerMainThreadRunnable::Dispatch, because API exposure checks
-// can't throw.  Maybe we should change it so they _could_ throw.  But for now
-// we are bad people and should be ashamed of ourselves.  Let's hope none of
-// them happen while a worker is shutting down.
-//
-// Do NOT copy what this class is doing elsewhere.  Just don't.
-class WorkerCheckAPIExposureOnMainThreadRunnable
-  : public WorkerMainThreadRunnable
-{
-public:
-  explicit
-  WorkerCheckAPIExposureOnMainThreadRunnable(WorkerPrivate* aWorkerPrivate);
-  virtual
-  ~WorkerCheckAPIExposureOnMainThreadRunnable();
-
-  // Returns whether the dispatch succeeded.  If this returns false, the API
-  // should not be exposed.
-  bool Dispatch();
-};
-
 // This runnable is used to stop a sync loop and it's meant to be used on the
 // main-thread only. As sync loops keep the busy count incremented as long as
 // they run this runnable does not modify the busy count