Bug 1634200 don't create a new global when the Worklet is finished r=padenot

When the worklet has already received the notification to shut down, there
will be no further notfication to release another global.

Differential Revision: https://phabricator.services.mozilla.com/D85975

dom/media/webaudio/AudioWorkletNode.cpp

@@ -247,7 +247,12 @@ void WorkletNodeEngine::ConstructProcessor(
     UniqueMessagePortId& aPortIdentifier, AudioNodeTrack* aTrack) {
   MOZ_ASSERT(mInputs.mPorts.empty() && mOutputs.mPorts.empty());
   RefPtr<AudioWorkletGlobalScope> global = aWorkletImpl->GetGlobalScope();
-  MOZ_ASSERT(global);  // global has already been used to register processor
+  if (!global) {
+    // A global was previously used to register this kind of processor.  If it
+    // no longer exists now, that is because the document is going away and so
+    // there is no need to send an error.
+    return;
+  }
   AutoJSAPI api;
   if (NS_WARN_IF(!api.Init(global))) {
     SendProcessorError(aTrack, nullptr);

dom/worklet/WorkletImpl.cpp

@@ -38,7 +38,8 @@ WorkletLoadInfo::WorkletLoadInfo(nsPIDOMWindowInner* aWindow)
 WorkletImpl::WorkletImpl(nsPIDOMWindowInner* aWindow, nsIPrincipal* aPrincipal)
     : mPrincipal(NullPrincipal::CreateWithInheritedAttributes(aPrincipal)),
       mWorkletLoadInfo(aWindow),
-      mTerminated(false) {
+      mTerminated(false),
+      mFinishedOnExecutionThread(false) {
   Unused << NS_WARN_IF(
       NS_FAILED(ipc::PrincipalToPrincipalInfo(mPrincipal, &mPrincipalInfo)));
 
@@ -67,6 +68,9 @@ dom::WorkletGlobalScope* WorkletImpl::GetGlobalScope() {
   if (mGlobalScope) {
     return mGlobalScope;
   }
+  if (mFinishedOnExecutionThread) {
+    return nullptr;
+  }
 
   dom::AutoJSAPI jsapi;
   jsapi.Init();
@@ -97,9 +101,12 @@ void WorkletImpl::NotifyWorkletFinished() {
   }
 
   // Release global scope on its thread.
-  SendControlMessage(NS_NewRunnableFunction(
-      "WorkletImpl::NotifyWorkletFinished",
-      [self = RefPtr<WorkletImpl>(this)]() { self->mGlobalScope = nullptr; }));
+  SendControlMessage(
+      NS_NewRunnableFunction("WorkletImpl::NotifyWorkletFinished",
+                             [self = RefPtr<WorkletImpl>(this)]() {
+                               self->mFinishedOnExecutionThread = true;
+                               self->mGlobalScope = nullptr;
+                             }));
 
   mTerminated = true;
   if (mWorkletThread) {

dom/worklet/WorkletImpl.h

@@ -100,6 +100,7 @@ class WorkletImpl {
 
   // Execution thread only.
   RefPtr<dom::WorkletGlobalScope> mGlobalScope;
+  bool mFinishedOnExecutionThread;
 
   Maybe<nsID> mAgentClusterId;