1 files changed, 87 insertions, 0 deletions
diff --git a/dom/base/GlobalTeardownObserver.h b/dom/base/GlobalTeardownObserver.h
new file mode 100644
index 0000000000..e6e3a56299
--- /dev/null
+++ b/dom/base/GlobalTeardownObserver.h
@@ -0,0 +1,87 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef DOM_BASE_GLOBALTEARDOWNOBSERVER_H_
+#define DOM_BASE_GLOBALTEARDOWNOBSERVER_H_
+
+#include "mozilla/Attributes.h"
+#include "mozilla/dom/EventTarget.h"
+#include "mozilla/RefPtr.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsID.h"
+#include "nsIGlobalObject.h"
+#include "nsIScriptGlobalObject.h"
+#include "nsISupports.h"
+#include "nsISupportsUtils.h"
+#include "nsPIDOMWindow.h"
+
+#define NS_GLOBALTEARDOWNOBSERVER_IID                \
+  {                                                  \
+    0xc31fddb9, 0xec49, 0x4f24, {                    \
+      0x90, 0x16, 0xb5, 0x2b, 0x26, 0x6c, 0xb6, 0x29 \
+    }                                                \
+  }
+
+namespace mozilla {
+
+class GlobalTeardownObserver
+    : public nsISupports,
+      public LinkedListElement<GlobalTeardownObserver> {
+ public:
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_GLOBALTEARDOWNOBSERVER_IID)
+
+  GlobalTeardownObserver();
+  explicit GlobalTeardownObserver(nsIGlobalObject* aGlobalObject,
+                                  bool aHasOrHasHadOwnerWindow = false);
+
+  nsPIDOMWindowInner* GetOwner() const { return mOwnerWindow; }
+  nsIGlobalObject* GetOwnerGlobal() const { return mParentObject; }
+  bool HasOrHasHadOwner() { return mHasOrHasHadOwnerWindow; }
+
+  void GetParentObject(nsIScriptGlobalObject** aParentObject) {
+    if (mParentObject) {
+      CallQueryInterface(mParentObject, aParentObject);
+    } else {
+      *aParentObject = nullptr;
+    }
+  }
+
+  virtual void DisconnectFromOwner();
+
+  // A global permanently becomes invalid when DisconnectEventTargetObjects() is
+  // called.  Normally this means:
+  // - For the main thread, when nsGlobalWindowInner::FreeInnerObjects is
+  //   called.
+  // - For a worker thread, when clearing the main event queue.  (Which we do
+  //   slightly later than when the spec notionally calls for it to be done.)
+  //
+  // A global may also become temporarily invalid when:
+  // - For the main thread, if the window is no longer the WindowProxy's current
+  //   inner window due to being placed in the bfcache.
+  nsresult CheckCurrentGlobalCorrectness() const;
+
+ protected:
+  virtual ~GlobalTeardownObserver();
+
+  void BindToOwner(nsIGlobalObject* aOwner);
+
+ private:
+  // The parent global object.  The global will clear this when
+  // it is destroyed by calling DisconnectFromOwner().
+  nsIGlobalObject* MOZ_NON_OWNING_REF mParentObject = nullptr;
+  // mParentObject pre QI-ed and cached (inner window)
+  // (it is needed for off main thread access)
+  // It is obtained in BindToOwner and reset in DisconnectFromOwner.
+  nsPIDOMWindowInner* MOZ_NON_OWNING_REF mOwnerWindow = nullptr;
+  bool mHasOrHasHadOwnerWindow = false;
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(GlobalTeardownObserver,
+                              NS_GLOBALTEARDOWNOBSERVER_IID)
+
+}  // namespace mozilla
+
+#endif