From 209a34c2b7031851631b0b059071a8d3ececab00 Mon Sep 17 00:00:00 2001
From: Karl Tomlinson <karlt+@karlt.net>
Date: Fri, 12 Jun 2020 03:53:34 +0000
Subject: [PATCH] Bug 1642849 shut down MediaTrackGraph from AudioContext when
 window will be destroyed r=padenot

Differential Revision: https://phabricator.services.mozilla.com/D74814
---
 dom/base/nsGlobalWindowInner.cpp            |  2 +-
 dom/media/webaudio/AudioContext.cpp         | 19 ++++++++++++++-----
 dom/media/webaudio/AudioContext.h           |  2 +-
 dom/media/webaudio/AudioDestinationNode.cpp |  5 +----
 4 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/dom/base/nsGlobalWindowInner.cpp b/dom/base/nsGlobalWindowInner.cpp
index bb4986d7f9b9..10c4f9e1d107 100644
--- a/dom/base/nsGlobalWindowInner.cpp
+++ b/dom/base/nsGlobalWindowInner.cpp
@@ -1137,7 +1137,7 @@ void nsGlobalWindowInner::FreeInnerObjects() {
   NotifyWindowIDDestroyed("inner-window-destroyed");
 
   for (uint32_t i = 0; i < mAudioContexts.Length(); ++i) {
-    mAudioContexts[i]->Shutdown();
+    mAudioContexts[i]->OnWindowDestroy();
   }
   mAudioContexts.Clear();
 
diff --git a/dom/media/webaudio/AudioContext.cpp b/dom/media/webaudio/AudioContext.cpp
index 8543fee9b1ab..b4d373f3afea 100644
--- a/dom/media/webaudio/AudioContext.cpp
+++ b/dom/media/webaudio/AudioContext.cpp
@@ -743,11 +743,11 @@ nsISerialEventTarget* AudioContext::GetMainThread() const {
 
 void AudioContext::DisconnectFromOwner() {
   mIsDisconnecting = true;
-  Shutdown();
+  OnWindowDestroy();
   DOMEventTargetHelper::DisconnectFromOwner();
 }
 
-void AudioContext::Shutdown() {
+void AudioContext::OnWindowDestroy() {
   // Avoid resend the Telemetry data.
   if (!mIsShutDown) {
     MaybeUpdateAutoplayTelemetryWhenShutdown();
@@ -776,9 +776,18 @@ void AudioContext::Shutdown() {
   // PBrowser::Destroy() message before xpcom shutdown begins.
   ShutdownWorklet();
 
-  // For offline contexts, we can destroy the MediaTrackGraph at this point.
-  if (mIsOffline && mDestination) {
-    mDestination->OfflineShutdown();
+  if (mDestination) {
+    // We can destroy the MediaTrackGraph at this point.
+    // Although there may be other clients using the graph, this graph is used
+    // only for clients in the same window and this window is going away.
+    // This will also interrupt any worklet script still running on the graph
+    // thread.
+    Graph()->ForceShutDown();
+    // AudioDestinationNodes on rendering offline contexts have a
+    // self-reference which needs removal.
+    if (mIsOffline) {
+      mDestination->OfflineShutdown();
+    }
   }
 }
 
diff --git a/dom/media/webaudio/AudioContext.h b/dom/media/webaudio/AudioContext.h
index 1812e79bcefb..ccc834ff9a23 100644
--- a/dom/media/webaudio/AudioContext.h
+++ b/dom/media/webaudio/AudioContext.h
@@ -151,7 +151,7 @@ class AudioContext final : public DOMEventTargetHelper,
 
   virtual void DisconnectFromOwner() override;
 
-  void Shutdown();  // idempotent
+  void OnWindowDestroy();  // idempotent
 
   JSObject* WrapObject(JSContext* aCx,
                        JS::Handle<JSObject*> aGivenProto) override;
diff --git a/dom/media/webaudio/AudioDestinationNode.cpp b/dom/media/webaudio/AudioDestinationNode.cpp
index b18ea7a2969b..67f6c7dceda2 100644
--- a/dom/media/webaudio/AudioDestinationNode.cpp
+++ b/dom/media/webaudio/AudioDestinationNode.cpp
@@ -488,10 +488,7 @@ void AudioDestinationNode::OfflineShutdown() {
   MOZ_ASSERT(Context() && Context()->IsOffline(),
              "Should only be called on a valid OfflineAudioContext");
 
-  if (mTrack) {
-    mTrack->Graph()->MediaTrackGraph::ForceShutDown();
-    mOfflineRenderingRef.Drop(this);
-  }
+  mOfflineRenderingRef.Drop(this);
 }
 
 JSObject* AudioDestinationNode::WrapObject(JSContext* aCx,