Bug 1728665. Use IsRootContentDocumentCrossProcess for a few places dealing with visual scroll offsets. r=botond

Visual scroll offsets can only differ on the cross process root content document.

Differential Revision: https://phabricator.services.mozilla.com/D124257

docshell/base/nsDocShell.cpp

@@ -4932,7 +4932,7 @@ nsresult nsDocShell::SetCurScrollPosEx(int32_t aCurHorizontalPos,
   NS_ENSURE_TRUE(presContext, NS_ERROR_FAILURE);
 
   // Only the root content document can have a distinct visual viewport offset.
-  if (!presContext->IsRootContentDocument()) {
+  if (!presContext->IsRootContentDocumentCrossProcess()) {
     return NS_OK;
   }
 

dom/base/nsDOMWindowUtils.cpp

@@ -1699,7 +1699,8 @@ nsDOMWindowUtils::ScrollToVisual(float aOffsetX, float aOffsetY,
   NS_ENSURE_TRUE(presContext, NS_ERROR_NOT_AVAILABLE);
 
   // This should only be called on the root content document.
-  NS_ENSURE_TRUE(presContext->IsRootContentDocument(), NS_ERROR_INVALID_ARG);
+  NS_ENSURE_TRUE(presContext->IsRootContentDocumentCrossProcess(),
+                 NS_ERROR_INVALID_ARG);
 
   FrameMetrics::ScrollOffsetUpdateType updateType;
   switch (aUpdateType) {

toolkit/components/sessionstore/SessionStoreUtils.cpp

@@ -309,7 +309,7 @@ void SessionStoreUtils::RestoreScrollPosition(
 
   if (nsCOMPtr<Document> doc = aWindow.GetExtantDoc()) {
     if (nsPresContext* presContext = doc->GetPresContext()) {
-      if (presContext->IsRootContentDocument()) {
+      if (presContext->IsRootContentDocumentCrossProcess()) {
         // Use eMainThread so this takes precedence over session history
         // (ScrollFrameHelper::ScrollToRestoredPosition()).
         presContext->PresShell()->ScrollToVisual(