Bug 1761040 - Prefix thread safety macros with MOZ_ r=geckoview-reviewers,media-playback-reviewers,alwu,jesup,m_kato

Differential Revision: https://phabricator.services.mozilla.com/D152575

dom/websocket/WebSocket.cpp

@@ -248,7 +248,7 @@ class WebSocketImpl final : public nsIInterfaceRequestor,
 
   // This mutex protects mWorkerShuttingDown.
   mozilla::Mutex mMutex;
-  bool mWorkerShuttingDown GUARDED_BY(mMutex);
+  bool mWorkerShuttingDown MOZ_GUARDED_BY(mMutex);
 
   RefPtr<WebSocketEventService> mService;
   nsCOMPtr<nsIPrincipal> mLoadingPrincipal;