Bug 1698601 - Part 2: Carry over restore data to new context after a process swap, r=smaug

Also, make sure we update layout history state from docshell before we load a
new URI, as it might be our last chance to do so before a process swap.

Differential Revision: https://phabricator.services.mozilla.com/D110994

docshell/base/CanonicalBrowsingContext.cpp

@@ -175,14 +175,13 @@ void CanonicalBrowsingContext::ReplacedBy(
   }
   aNewContext->mWebProgress = std::move(mWebProgress);
 
-  // Bug 1698601 - We'll eventually want to copy this data over to the new
-  // context instead of clearing it completely.
+  bool hasRestoreData = !!mRestoreData && !mRestoreData->IsEmpty();
+  aNewContext->mRestoreData = std::move(mRestoreData);
+  aNewContext->mRequestedContentRestores = mRequestedContentRestores;
+  aNewContext->mCompletedContentRestores = mCompletedContentRestores;
   SetRestoreData(nullptr);
   mRequestedContentRestores = 0;
   mCompletedContentRestores = 0;
-  aNewContext->mRestoreData = nullptr;
-  aNewContext->mRequestedContentRestores = 0;
-  aNewContext->mCompletedContentRestores = 0;
 
   // Use the Transaction for the fields which need to be updated whether or not
   // the new context has been attached before.
@@ -191,7 +190,7 @@ void CanonicalBrowsingContext::ReplacedBy(
   txn.SetBrowserId(GetBrowserId());
   txn.SetHistoryID(GetHistoryID());
   txn.SetExplicitActive(GetExplicitActive());
-  txn.SetHasRestoreData(false);
+  txn.SetHasRestoreData(hasRestoreData);
   if (aNewContext->EverAttached()) {
     MOZ_ALWAYS_SUCCEEDS(txn.Commit(aNewContext));
   } else {

docshell/base/nsDocShell.cpp

@@ -10215,6 +10215,11 @@ nsresult nsDocShell::DoURILoad(nsDocShellLoadState* aLoadState,
     return NS_ERROR_UNEXPECTED;
   }
 
+  // Persist and sync layout history state before we load a new uri, as this
+  // might be our last chance to do so, in the content process.
+  PersistLayoutHistoryState();
+  SynchronizeLayoutHistoryState();
+
   nsresult rv;
   nsContentPolicyType contentPolicyType = DetermineContentType();