Bug 1700719 - Discard-check both the top-level and current context before restoring, r=nika

Differential Revision: https://phabricator.services.mozilla.com/D109722

docshell/base/CanonicalBrowsingContext.cpp

@@ -1745,6 +1745,8 @@ void CanonicalBrowsingContext::SetRestoreData(SessionStoreRestoreData* aData) {
 
 void CanonicalBrowsingContext::RequestRestoreTabContent(
     WindowGlobalParent* aWindow) {
+  MOZ_DIAGNOSTIC_ASSERT(IsTop());
+
   if (IsDiscarded() || !mRestoreData || mRestoreData->IsEmpty()) {
     return;
   }

dom/ipc/WindowGlobalParent.cpp

@@ -1294,9 +1294,9 @@ mozilla::ipc::IPCResult WindowGlobalParent::RecvResetSessionStore(
 }
 
 mozilla::ipc::IPCResult WindowGlobalParent::RecvRequestRestoreTabContent() {
-  CanonicalBrowsingContext* bc = BrowsingContext()->Top();
-  if (bc && !bc->IsDiscarded()) {
-    bc->RequestRestoreTabContent(this);
+  CanonicalBrowsingContext* bc = BrowsingContext();
+  if (bc && bc->AncestorsAreCurrent()) {
+    bc->Top()->RequestRestoreTabContent(this);
   }
   return IPC_OK();
 }