Bug 1538979 - Part 2: Add WillDestroy and DidDestroy lifecycle methods on JSWindowActor; r=nika

Differential Revision: https://phabricator.services.mozilla.com/D30196

--HG--
extra : moz-landing-system : lando

dom/chrome-webidl/JSWindowActor.webidl

@@ -51,3 +51,12 @@ JSWindowActorChild implements JSWindowActor;
 callback interface MozObserverCallback {
   void observe(nsISupports subject, ByteString topic, DOMString? data);
 };
+
+// WebIDL callback interface calling the `willDestroy` and `didDestroy`
+// method on JSWindowActors.
+callback MozActorDestroyCallback = void();
+
+dictionary MozActorDestroyCallbacks {
+  [ChromeOnly] MozActorDestroyCallback willDestroy;
+  [ChromeOnly] MozActorDestroyCallback didDestroy;
+};

dom/ipc/JSWindowActor.cpp

@@ -39,6 +39,37 @@ nsIGlobalObject* JSWindowActor::GetParentObject() const {
   return xpc::NativeGlobal(xpc::PrivilegedJunkScope());
 }
 
+void JSWindowActor::StartDestroy() {
+  DestroyCallback(DestroyCallbackFunction::WillDestroy);
+}
+
+void JSWindowActor::AfterDestroy() {
+  DestroyCallback(DestroyCallbackFunction::DidDestroy);
+}
+
+void JSWindowActor::DestroyCallback(DestroyCallbackFunction callback) {
+  AutoEntryScript aes(xpc::PrivilegedJunkScope(),
+                      "JSWindowActor destroy callback");
+  JSContext* cx = aes.cx();
+  MozActorDestroyCallbacks callbacksHolder;
+  NS_ENSURE_TRUE_VOID(GetWrapper());
+  JS::Rooted<JS::Value> val(cx, JS::ObjectValue(*GetWrapper()));
+  if (NS_WARN_IF(!callbacksHolder.Init(cx, val))) {
+    return;
+  }
+
+  // Destroy callback is optional.
+  if (callback == DestroyCallbackFunction::WillDestroy) {
+    if (callbacksHolder.mWillDestroy.WasPassed()) {
+      callbacksHolder.mWillDestroy.Value()->Call();
+    }
+  } else {
+    if (callbacksHolder.mDidDestroy.WasPassed()) {
+      callbacksHolder.mDidDestroy.Value()->Call();
+    }
+  }
+}
+
 void JSWindowActor::RejectPendingQueries() {
   // Take our queries out, in case somehow rejecting promises can trigger
   // additions or removals.

dom/ipc/JSWindowActor.h

@@ -39,6 +39,7 @@ class JSWindowActor : public nsISupports, public nsWrapperCache {
   JSWindowActor();
 
   enum class Type { Parent, Child };
+  enum class DestroyCallbackFunction { WillDestroy, DidDestroy };
 
   const nsString& Name() const { return mName; }
 
@@ -71,6 +72,12 @@ class JSWindowActor : public nsISupports, public nsWrapperCache {
 
   void SetName(const nsAString& aName);
 
+  void StartDestroy();
+
+  void AfterDestroy();
+
+  void DestroyCallback(DestroyCallbackFunction willDestroy);
+
  private:
   void ReceiveMessageOrQuery(JSContext* aCx,
                              const JSWindowActorMessageMeta& aMetadata,

dom/ipc/JSWindowActorChild.cpp

@@ -115,10 +115,12 @@ Nullable<WindowProxyHolder> JSWindowActorChild::GetContentWindow(
 }
 
 void JSWindowActorChild::StartDestroy() {
+  JSWindowActor::StartDestroy();
   mCanSend = false;
 }
 
 void JSWindowActorChild::AfterDestroy() {
+  JSWindowActor::AfterDestroy();
   mManager = nullptr;
 }
 

dom/ipc/JSWindowActorParent.cpp

@@ -86,10 +86,12 @@ void JSWindowActorParent::SendRawMessage(const JSWindowActorMessageMeta& aMeta,
 }
 
 void JSWindowActorParent::StartDestroy() {
+  JSWindowActor::StartDestroy();
   mCanSend = false;
 }
 
 void JSWindowActorParent::AfterDestroy() {
+  JSWindowActor::AfterDestroy();
   mManager = nullptr;
 }