Bug 1752100 - Make sure nsWSAdmissionManager::ConnectNext is called on main thread, r=necko-reviewers,valentin

Differential Revision: https://phabricator.services.mozilla.com/D137267

netwerk/protocol/websocket/WebSocketChannel.cpp

@@ -399,14 +399,38 @@ class nsWSAdmissionManager {
       }
     }
 
-    if (aChannel->mConnecting) {
+    if (NS_IsMainThread()) {
+      ContinueOnStopSession(aChannel, aReason);
+    } else {
+      NS_DispatchToMainThread(NS_NewRunnableFunction(
+          "nsWSAdmissionManager::ContinueOnStopSession",
+          [channel = RefPtr{aChannel}, reason = aReason]() {
+            StaticMutexAutoLock lock(sLock);
+            if (!sManager) {
+              return;
+            }
+
+            nsWSAdmissionManager::ContinueOnStopSession(channel, reason);
+          }));
+    }
+  }
+
+  static void ContinueOnStopSession(WebSocketChannel* aChannel,
+                                    nsresult aReason) {
+    sLock.AssertCurrentThreadOwns();
     MOZ_ASSERT(NS_IsMainThread(), "not main thread");
 
-      // Only way a connecting channel may get here w/o failing is if it was
-      // closed with GOING_AWAY (1001) because of navigation, tab close, etc.
+    if (!aChannel->mConnecting) {
+      return;
+    }
+
+    // Only way a connecting channel may get here w/o failing is if it
+    // was closed with GOING_AWAY (1001) because of navigation, tab
+    // close, etc.
     MOZ_ASSERT(
         NS_FAILED(aReason) || aChannel->mScriptCloseCode == CLOSE_GOING_AWAY,
         "websocket closed while connecting w/o failing?");
+    Unused << aReason;
 
     sManager->RemoveFromQueue(aChannel);
 
@@ -417,7 +441,6 @@ class nsWSAdmissionManager {
       sManager->ConnectNext(aChannel->mAddress, aChannel->mOriginSuffix);
     }
   }
-  }
 
   static void IncrementSessionCount() {
     StaticMutexAutoLock lock(sLock);