From 7124231a9c8baa8f63225df239093cc0a442f57b Mon Sep 17 00:00:00 2001
From: "mscott%netscape.com"
 <mscott%netscape.com@18797224-902f-48f8-a5cc-f745e15eee43>
Date: Fri, 13 Jul 2001 04:53:58 +0000
Subject: [PATCH] Bug #89628 --> don't create a session history entry if there
 is no session history for this docshell chain. Fixes the problem where the
 mailnews message pane was suddenly getting the scroll bar state remembered
 across messages. (checking in for radha) r=valeski sr=mscott

git-svn-id: svn://10.0.0.236/trunk@99159 18797224-902f-48f8-a5cc-f745e15eee43
---
 mozilla/docshell/base/nsDocShell.cpp | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/mozilla/docshell/base/nsDocShell.cpp b/mozilla/docshell/base/nsDocShell.cpp
index 3325f6b17ea..696bf9fa4da 100644
--- a/mozilla/docshell/base/nsDocShell.cpp
+++ b/mozilla/docshell/base/nsDocShell.cpp
@@ -4958,6 +4958,7 @@ nsDocShell::OnNewURI(nsIURI * aURI, nsIChannel * aChannel,
     UpdateCurrentGlobalHistory();
     PRBool updateHistory = PR_TRUE;
     PRBool equalUri = PR_FALSE;
+    PRBool shAvailable = PR_TRUE;
 
     // Get the post data from the channel
     nsCOMPtr<nsIInputStream> inputStream;
@@ -4968,6 +4969,26 @@ nsDocShell::OnNewURI(nsIURI * aURI, nsIChannel * aChannel,
             httpChannel->GetUploadStream(getter_AddRefs(inputStream));
         }
     }
+    /* Create SH Entry (mLSHE) only if there is a  SessionHistory object (mSessionHistory) in
+     * the current frame or in the root docshell
+     */
+
+    if (!mSessionHistory) {
+      nsCOMPtr<nsIDocShellTreeItem> root;
+      //Get the root docshell
+      GetSameTypeRootTreeItem(getter_AddRefs(root));
+      if (root) {
+        // QI root to nsIWebNavigation
+        nsCOMPtr<nsIWebNavigation> rootAsWebnav(do_QueryInterface(root));
+        if (rootAsWebnav) {
+          // Get the handle to SH from the root docshell
+          nsCOMPtr<nsISHistory> rootSH;
+          rootAsWebnav->GetSessionHistory(getter_AddRefs(rootSH));
+          if (!rootSH)
+            shAvailable = PR_FALSE;
+        }
+      }
+    }  // mSessionHistory
     // Determine if this type of load should update history
     if (aLoadType & LOAD_FLAGS_BYPASS_HISTORY ||
         aLoadType & LOAD_CMD_RELOAD || aLoadType & LOAD_CMD_HISTORY ||
@@ -4976,8 +4997,8 @@ nsDocShell::OnNewURI(nsIURI * aURI, nsIChannel * aChannel,
         updateHistory = PR_FALSE;
     }
 
-    if (updateHistory) {        // Page load not from SH
-        // Update session history if necessary...
+    if (updateHistory && shAvailable) { 
+      // Update session history if necessary...
         if (!mLSHE && (mItemType == typeContent) && mURIResultedInDocument) {
             /* This is  a fresh page getting loaded for the first time
              *.Create a Entry for it and add it to SH, if this is the