diff --git a/dom/gamepad/GamepadPlatformService.cpp b/dom/gamepad/GamepadPlatformService.cpp
index a4d92d84bfa1..0397646dd977 100644
--- a/dom/gamepad/GamepadPlatformService.cpp
+++ b/dom/gamepad/GamepadPlatformService.cpp
@@ -28,33 +28,44 @@ StaticRefPtr<GamepadPlatformService> gGamepadPlatformServiceSingleton;
 
 }  // namespace
 
-GamepadPlatformService::MonitoringState::~MonitoringState() {
-  AssertIsOnBackgroundThread();
-  MOZ_RELEASE_ASSERT(mObservers.IsEmpty());
+// static
+GamepadMonitoringState& GamepadMonitoringState::GetSingleton() {
+  static GamepadMonitoringState sInstance{};
+  return sInstance;
 }
 
-void GamepadPlatformService::MonitoringState::AddObserver(
-    WeakPtr<GamepadTestChannelParent> aParent) {
+void GamepadMonitoringState::AddObserver(GamepadTestChannelParent* aParent) {
   AssertIsOnBackgroundThread();
   MOZ_ASSERT(aParent);
-  MOZ_ASSERT(!mObservers.Contains(aParent));
-  mObservers.AppendElement(std::move(aParent));
+  MOZ_ALWAYS_TRUE(mObservers.append(aParent));
 }
 
-void GamepadPlatformService::MonitoringState::RemoveObserver(
-    GamepadTestChannelParent* aParent) {
+void GamepadMonitoringState::RemoveObserver(GamepadTestChannelParent* aParent) {
   AssertIsOnBackgroundThread();
   MOZ_ASSERT(aParent);
-  MOZ_ASSERT(mObservers.Contains(aParent));
-  mObservers.RemoveElement(aParent);
+
+  WeakPtr<GamepadTestChannelParent>* observer = nullptr;
+
+  for (auto& item : mObservers) {
+    if (item == aParent) {
+      observer = &item;
+    }
+  }
+
+  MOZ_ASSERT(
+      observer,
+      "Attempted to remove a GamepadTestChannelParent that was never added");
+
+  std::swap(*observer, mObservers.back());
+  mObservers.popBack();
 }
 
-bool GamepadPlatformService::MonitoringState::IsMonitoring() const {
+bool GamepadMonitoringState::IsMonitoring() const {
   AssertIsOnBackgroundThread();
   return mIsMonitoring;
 }
 
-void GamepadPlatformService::MonitoringState::Set(bool aIsMonitoring) {
+void GamepadMonitoringState::Set(bool aIsMonitoring) {
   AssertIsOnBackgroundThread();
 
   if (mIsMonitoring != aIsMonitoring) {
@@ -258,7 +269,7 @@ void GamepadPlatformService::AddChannelParent(
 
   StartGamepadMonitoring();
 
-  mMonitoringState.Set(true);
+  GamepadMonitoringState::GetSingleton().Set(true);
 }
 
 void GamepadPlatformService::RemoveChannelParent(
@@ -278,7 +289,7 @@ void GamepadPlatformService::RemoveChannelParent(
     }
   }
 
-  mMonitoringState.Set(false);
+  GamepadMonitoringState::GetSingleton().Set(false);
 
   StopGamepadMonitoring();
   ResetGamepadIndexes();
diff --git a/dom/gamepad/GamepadPlatformService.h b/dom/gamepad/GamepadPlatformService.h
index 608f27db8e76..70a86b14518d 100644
--- a/dom/gamepad/GamepadPlatformService.h
+++ b/dom/gamepad/GamepadPlatformService.h
@@ -12,6 +12,7 @@
 #include <map>
 #include "mozilla/Mutex.h"
 #include "mozilla/StaticPtr.h"
+#include "mozilla/Vector.h"
 #include "mozilla/WeakPtr.h"
 
 namespace mozilla {
@@ -23,6 +24,33 @@ enum class GamepadLightIndicatorType : uint8_t;
 struct GamepadPoseState;
 class GamepadTestChannelParent;
 struct GamepadTouchState;
+class GamepadPlatformService;
+
+class GamepadMonitoringState {
+ public:
+  static GamepadMonitoringState& GetSingleton();
+
+  void AddObserver(GamepadTestChannelParent* aParent);
+  void RemoveObserver(GamepadTestChannelParent* aParent);
+
+  bool IsMonitoring() const;
+
+  GamepadMonitoringState(const GamepadMonitoringState&) = delete;
+  GamepadMonitoringState(GamepadMonitoringState&&) = delete;
+  GamepadMonitoringState& operator=(const GamepadMonitoringState) = delete;
+  GamepadMonitoringState& operator=(GamepadMonitoringState&&) = delete;
+
+ private:
+  GamepadMonitoringState() = default;
+  ~GamepadMonitoringState() = default;
+
+  void Set(bool aIsMonitoring);
+
+  bool mIsMonitoring{false};
+  Vector<WeakPtr<GamepadTestChannelParent>> mObservers;
+
+  friend class mozilla::dom::GamepadPlatformService;
+};
 
 // Platform Service for building and transmitting IPDL messages
 // through the HAL sandbox. Used by platform specific
@@ -39,30 +67,6 @@ struct GamepadTouchState;
 class GamepadPlatformService final {
   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(GamepadPlatformService)
  public:
-  class MonitoringState {
-   public:
-    MonitoringState() = default;
-    ~MonitoringState();
-
-    void AddObserver(WeakPtr<GamepadTestChannelParent> aParent);
-    void RemoveObserver(GamepadTestChannelParent* aParent);
-
-    bool IsMonitoring() const;
-
-    MonitoringState(const MonitoringState&) = delete;
-    MonitoringState(MonitoringState&&) = delete;
-    MonitoringState& operator=(const MonitoringState) = delete;
-    MonitoringState& operator=(MonitoringState&&) = delete;
-
-   private:
-    void Set(bool aIsMonitoring);
-
-    bool mIsMonitoring{false};
-    nsTArray<WeakPtr<GamepadTestChannelParent>> mObservers;
-
-    friend class GamepadPlatformService;
-  };
-
   // Get the singleton service
   static already_AddRefed<GamepadPlatformService> GetParentService();
 
@@ -117,8 +121,6 @@ class GamepadPlatformService final {
 
   void MaybeShutdown();
 
-  MonitoringState& GetMonitoringState() { return mMonitoringState; }
-
  private:
   GamepadPlatformService();
   ~GamepadPlatformService();
@@ -140,8 +142,6 @@ class GamepadPlatformService final {
   Mutex mMutex;
 
   std::map<uint32_t, GamepadAdded> mGamepadAdded;
-
-  MonitoringState mMonitoringState;
 };
 
 }  // namespace dom
diff --git a/dom/gamepad/ipc/GamepadTestChannelParent.cpp b/dom/gamepad/ipc/GamepadTestChannelParent.cpp
index dc66454400a1..267a1b968b93 100644
--- a/dom/gamepad/ipc/GamepadTestChannelParent.cpp
+++ b/dom/gamepad/ipc/GamepadTestChannelParent.cpp
@@ -19,20 +19,12 @@ already_AddRefed<GamepadTestChannelParent> GamepadTestChannelParent::Create() {
 
 GamepadTestChannelParent::GamepadTestChannelParent() {
   ::mozilla::ipc::AssertIsOnBackgroundThread();
-  RefPtr<GamepadPlatformService> service =
-      GamepadPlatformService::GetParentService();
-  MOZ_ASSERT(service);
-
-  service->GetMonitoringState().AddObserver(this);
+  GamepadMonitoringState::GetSingleton().AddObserver(this);
 }
 
 GamepadTestChannelParent::~GamepadTestChannelParent() {
   ::mozilla::ipc::AssertIsOnBackgroundThread();
-  RefPtr<GamepadPlatformService> service =
-      GamepadPlatformService::GetParentService();
-  MOZ_ASSERT(service);
-
-  service->GetMonitoringState().RemoveObserver(this);
+  GamepadMonitoringState::GetSingleton().RemoveObserver(this);
 }
 
 void GamepadTestChannelParent::AddGamepadToPlatformService(
@@ -80,7 +72,7 @@ mozilla::ipc::IPCResult GamepadTestChannelParent::RecvGamepadTestEvent(
   // started. Everything else won't be deferred and will fail if monitoring
   // isn't running
   if (body.type() == GamepadChangeEventBody::TGamepadAdded) {
-    if (service->GetMonitoringState().IsMonitoring()) {
+    if (GamepadMonitoringState::GetSingleton().IsMonitoring()) {
       AddGamepadToPlatformService(aID, body.get_GamepadAdded());
     } else {
       mDeferredGamepadAdded.AppendElement(
@@ -89,7 +81,7 @@ mozilla::ipc::IPCResult GamepadTestChannelParent::RecvGamepadTestEvent(
     return IPC_OK();
   }
 
-  if (!service->GetMonitoringState().IsMonitoring()) {
+  if (!GamepadMonitoringState::GetSingleton().IsMonitoring()) {
     return IPC_FAIL(this, "Simulated message received while not monitoring");
   }