Issue #1442 - Part 23 - Align FetchStream with Firefox 68ESR. https://bugzilla.mozilla.org/show_bug.cgi?id=1612308 https://bugzilla.mozilla.org/show_bug.cgi?id=1445587 Partial part 2 implementing synchronization changes.

dom/fetch/FetchStream.h

@@ -52,6 +52,14 @@ private:
               nsIInputStream* aInputStream);
   ~FetchStream();
 
+#ifdef DEBUG
+  void
+  AssertIsOnOwningThread();
+#else
+  void
+  AssertIsOnOwningThread() {}
+#endif
+
   static void
   RequestDataCallback(JSContext* aCx, JS::HandleObject aStream,
                       void* aUnderlyingSource, uint8_t aFlags,
@@ -81,10 +89,19 @@ private:
   FinalizeCallback(void* aUnderlyingSource, uint8_t aFlags);
 
   void
-  ErrorPropagation(JSContext* aCx, JS::HandleObject aStream, nsresult aRv);
+  ErrorPropagation(JSContext* aCx,
+                   const MutexAutoLock& aProofOfLock,
+                   JS::HandleObject aStream, nsresult aRv);
 
   void
-  CloseAndReleaseObjects(JSContext* aCx, JS::HandleObject aStream);
+  CloseAndReleaseObjects(JSContext* aCx,
+                         const MutexAutoLock& aProofOfLock,
+                         JS::HandleObject aSteam);
+
+  class WorkerShutdown;
+
+  void
+  ReleaseObjects(const MutexAutoLock& aProofOfLock);
 
   void
   ReleaseObjects();
@@ -92,6 +109,9 @@ private:
   // Common methods
 
   enum State {
+    // This is the beginning state before any reading operation.
+    eInitializing,
+
     // RequestDataCallback has not been called yet. We haven't started to read
     // data from the stream yet.
     eWaiting,
@@ -111,7 +131,12 @@ private:
     eClosed,
   };
 
-  // Touched only on the target thread.
+  // We need a mutex because JS engine can release FetchStream on a non-owning
+  // thread. We must be sure that the releasing of resources doesn't trigger
+  // race conditions.
+  Mutex mMutex;
+
+  // Protected by mutex.
   State mState;
 
   nsCOMPtr<nsIGlobalObject> mGlobal;