From 00ffaf83c0e118c9b0c7deeb7ad3d91cf5c7ede1 Mon Sep 17 00:00:00 2001
From: Peter Van der Beken <peterv@propagandism.org>
Date: Tue, 23 Nov 2021 15:37:24 +0000
Subject: [PATCH] Bug 1741132 - Add a property for whether an entry is in the
 BFCache (holds a content viewer or a frame loader). r=smaug

Differential Revision: https://phabricator.services.mozilla.com/D131893
---
 docshell/shistory/SessionHistoryEntry.cpp   | 6 ++++++
 docshell/shistory/nsISHEntry.idl            | 2 ++
 docshell/shistory/nsSHEntry.cpp             | 6 ++++++
 docshell/shistory/nsSHistory.cpp            | 4 ++++
 docshell/test/chrome/bug396519_window.xhtml | 2 +-
 5 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/docshell/shistory/SessionHistoryEntry.cpp b/docshell/shistory/SessionHistoryEntry.cpp
index c43899387df1..3d9582be0314 100644
--- a/docshell/shistory/SessionHistoryEntry.cpp
+++ b/docshell/shistory/SessionHistoryEntry.cpp
@@ -595,6 +595,12 @@ SessionHistoryEntry::SetContentViewer(nsIContentViewer* aContentViewer) {
   return NS_ERROR_FAILURE;
 }
 
+NS_IMETHODIMP
+SessionHistoryEntry::GetIsInBFCache(bool* aResult) {
+  *aResult = !!SharedInfo()->mFrameLoader;
+  return NS_OK;
+}
+
 NS_IMETHODIMP
 SessionHistoryEntry::GetSticky(bool* aSticky) {
   *aSticky = SharedInfo()->mSticky;
diff --git a/docshell/shistory/nsISHEntry.idl b/docshell/shistory/nsISHEntry.idl
index 73ac40551d4e..ab8f86789138 100644
--- a/docshell/shistory/nsISHEntry.idl
+++ b/docshell/shistory/nsISHEntry.idl
@@ -110,6 +110,8 @@ interface nsISHEntry : nsISupports
     /** Content viewer, for fast restoration of presentation */
     [infallible] attribute nsIContentViewer contentViewer;
 
+    [infallible] readonly attribute boolean isInBFCache;
+
     /** Whether the content viewer is marked "sticky" */
     [infallible] attribute boolean sticky;
 
diff --git a/docshell/shistory/nsSHEntry.cpp b/docshell/shistory/nsSHEntry.cpp
index 1e4000eacd2b..7cf6372df8ab 100644
--- a/docshell/shistory/nsSHEntry.cpp
+++ b/docshell/shistory/nsSHEntry.cpp
@@ -996,6 +996,12 @@ nsSHEntry::GetContentViewer(nsIContentViewer** aResult) {
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsSHEntry::GetIsInBFCache(bool* aResult) {
+  *aResult = !!GetState()->mContentViewer;
+  return NS_OK;
+}
+
 NS_IMETHODIMP
 nsSHEntry::Clone(nsISHEntry** aResult) {
   nsCOMPtr<nsISHEntry> entry = new nsSHEntry(*this);
diff --git a/docshell/shistory/nsSHistory.cpp b/docshell/shistory/nsSHistory.cpp
index 82f86e318a21..c57e538e16d3 100644
--- a/docshell/shistory/nsSHistory.cpp
+++ b/docshell/shistory/nsSHistory.cpp
@@ -972,6 +972,10 @@ static void LogEntry(nsISHEntry* aEntry, int32_t aIndex, int32_t aTotal,
   MOZ_LOG(gSHLog, LogLevel::Debug,
           (" %s%s  Name = %s\n", prefix.get(), childCount > 0 ? "|" : " ",
            NS_LossyConvertUTF16toASCII(name).get()));
+  MOZ_LOG(
+      gSHLog, LogLevel::Debug,
+      (" %s%s  Is in BFCache = %s\n", prefix.get(), childCount > 0 ? "|" : " ",
+       aEntry->GetIsInBFCache() ? "true" : "false"));
 
   nsCOMPtr<nsISHEntry> prevChild;
   for (int32_t i = 0; i < childCount; ++i) {
diff --git a/docshell/test/chrome/bug396519_window.xhtml b/docshell/test/chrome/bug396519_window.xhtml
index 31fb6d296bcd..303f1eb6d907 100644
--- a/docshell/test/chrome/bug396519_window.xhtml
+++ b/docshell/test/chrome/bug396519_window.xhtml
@@ -69,7 +69,7 @@
         for (let i = 0; i < history.count; i++) {
           var shEntry = history.getEntryAtIndex(i).
                           QueryInterface(Ci.nsISHEntry);
-          is(!!shEntry.contentViewer, gExpected[i], "content viewer "+i+", test "+gTestCount);
+          is(shEntry.isInBFCache, gExpected[i], `BFCache for shentry[${i}], test ${gTestCount}`);
         }
 
         // Make sure none of the SHEntries share bfcache entries with one