Bug 1722880 - Part 1: Add IsInBFCache to WindowContext, and make it non-SHIP compatible, r=smaug,necko-reviewers,dragana

This field will be useful to JS code such as JSWindowActors which need to be
able to detect when their WindowContext is no longer active.

Differential Revision: https://phabricator.services.mozilla.com/D124098

docshell/base/WindowContext.cpp

@@ -18,6 +18,7 @@
 #include "mozilla/ClearOnShutdown.h"
 #include "nsGlobalWindowInner.h"
 #include "nsIScriptError.h"
+#include "nsIXULRuntime.h"
 #include "nsRefPtrHashtable.h"
 #include "nsContentUtils.h"
 
@@ -67,6 +68,13 @@ bool WindowContext::IsCurrent() const {
   return mBrowsingContext->mCurrentWindowContext == this;
 }
 
+bool WindowContext::IsInBFCache() {
+  if (mozilla::SessionHistoryInParent()) {
+    return mBrowsingContext->IsInBFCache();
+  }
+  return TopWindowContext()->GetWindowStateSaved();
+}
+
 nsGlobalWindowInner* WindowContext::GetInnerWindow() const {
   return mWindowGlobalChild ? mWindowGlobalChild->GetWindowGlobal() : nullptr;
 }
@@ -354,6 +362,12 @@ void WindowContext::DidSet(FieldIndex<IDX_HasReportedShadowDOMUsage>,
   }
 }
 
+bool WindowContext::CanSet(FieldIndex<IDX_WindowStateSaved>, bool aValue,
+                           ContentParent* aSource) {
+  return !mozilla::SessionHistoryInParent() && IsTop() &&
+         CheckOnlyOwningProcessCanSet(aSource);
+}
+
 void WindowContext::CreateFromIPC(IPCInitializer&& aInit) {
   MOZ_RELEASE_ASSERT(XRE_IsContentProcess(),
                      "Should be a WindowGlobalParent in the parent");