diff --git a/mozilla/docshell/base/Makefile.in b/mozilla/docshell/base/Makefile.in
index 36bafffcc8f..521264486d5 100644
--- a/mozilla/docshell/base/Makefile.in
+++ b/mozilla/docshell/base/Makefile.in
@@ -132,3 +132,5 @@ CPPSRCS		= \
 FORCE_STATIC_LIB = 1
 
 include $(topsrcdir)/config/rules.mk
+
+LOCAL_INCLUDES += -I$(srcdir)/../shistory/src
diff --git a/mozilla/docshell/base/nsDocShell.cpp b/mozilla/docshell/base/nsDocShell.cpp
index ebfcfa8cf13..98e8416ddfb 100644
--- a/mozilla/docshell/base/nsDocShell.cpp
+++ b/mozilla/docshell/base/nsDocShell.cpp
@@ -101,6 +101,7 @@
 #include "nsDocShellLoadInfo.h"
 #include "nsCDefaultURIFixup.h"
 #include "nsDocShellEnumerator.h"
+#include "nsSHistory.h"
 
 // Helper Classes
 #include "nsDOMError.h"
@@ -4964,15 +4965,8 @@ nsDocShell::CanSavePresentation(PRUint32 aLoadType,
 
     // Avoid doing the work of saving the presentation state in the case where
     // the content viewer cache is disabled.
-    nsCOMPtr<nsISHistory> rootSH;
-    GetRootSessionHistory(getter_AddRefs(rootSH));
-    if (rootSH) {
-      nsCOMPtr<nsISHistoryInternal> shistInt(do_QueryInterface(rootSH));
-      PRInt32 maxViewers;
-      shistInt->GetHistoryMaxTotalViewers(&maxViewers);
-      if (maxViewers == 0)
+    if (nsSHistory::GetMaxTotalViewers() == 0)
         return PR_FALSE;
-    }
 
     // Don't cache the content viewer if we're in a subframe and the subframe
     // pref is disabled.
diff --git a/mozilla/docshell/shistory/public/nsISHistoryInternal.idl b/mozilla/docshell/shistory/public/nsISHistoryInternal.idl
index 1c46b1d910d..1dfd5961c6b 100644
--- a/mozilla/docshell/shistory/public/nsISHistoryInternal.idl
+++ b/mozilla/docshell/shistory/public/nsISHistoryInternal.idl
@@ -51,7 +51,7 @@ interface nsIDocShell;
 #define NS_SHISTORY_INTERNAL_CONTRACTID "@mozilla.org/browser/shistory-internal;1"
 %}
 
-[scriptable, uuid(494fac3c-64f4-41b8-b209-b4ada899613b)]
+[scriptable, uuid(df8788d6-c0ed-4517-b47e-c719afc94284)]
 interface nsISHistoryInternal: nsISupports
 {
   /**
@@ -98,12 +98,4 @@ interface nsISHistoryInternal: nsISupports
    * the previous viewer.
    */
    void evictContentViewers(in long previousIndex, in long index);
-
-   /**
-    * Max number of total cached content viewers.  If the pref
-    * browser.sessionhistory.max_total_viewers is negative, then
-    * this value is calculated based on the total amount of memory.
-    * Otherwise, it comes straight from the pref.
-    */
-   readonly attribute long historyMaxTotalViewers;
 };
diff --git a/mozilla/docshell/shistory/src/nsSHistory.cpp b/mozilla/docshell/shistory/src/nsSHistory.cpp
index 7d0de15f6bf..9b536b9f2d3 100644
--- a/mozilla/docshell/shistory/src/nsSHistory.cpp
+++ b/mozilla/docshell/shistory/src/nsSHistory.cpp
@@ -112,7 +112,7 @@ nsSHistoryObserver::Observe(nsISupports *aSubject, const char *aTopic,
     prefs->GetIntPref(PREF_SHISTORY_MAX_TOTAL_VIEWERS,
                       &nsSHistory::sHistoryMaxTotalViewers);
     if (nsSHistory::sHistoryMaxTotalViewers < 0) {
-      nsSHistory::sHistoryMaxTotalViewers = nsSHistory::GetMaxTotalViewers();
+      nsSHistory::sHistoryMaxTotalViewers = nsSHistory::CalcMaxTotalViewers();
     }
 
     nsSHistory::EvictGlobalContentViewer();
@@ -158,16 +158,9 @@ NS_INTERFACE_MAP_END
 //    nsSHistory: nsISHistory
 //*****************************************************************************
 
-NS_IMETHODIMP
-nsSHistory::GetHistoryMaxTotalViewers(PRInt32 *max)
-{
-    *max = sHistoryMaxTotalViewers;
-    return NS_OK;
-}
-
 // static
 PRUint32
-nsSHistory::GetMaxTotalViewers()
+nsSHistory::CalcMaxTotalViewers()
 {
   // Calculate an estimate of how many ContentViewers we should cache based
   // on RAM.  This assumes that the average ContentViewer is 4MB (conservative)
@@ -262,7 +255,7 @@ nsSHistory::Startup()
   // If the pref is negative, that means we calculate how many viewers
   // we think we should cache, based on total memory
   if (sHistoryMaxTotalViewers < 0) {
-    sHistoryMaxTotalViewers = GetMaxTotalViewers();
+    sHistoryMaxTotalViewers = CalcMaxTotalViewers();
   }
 
   // Initialize the global list of all SHistory objects
diff --git a/mozilla/docshell/shistory/src/nsSHistory.h b/mozilla/docshell/shistory/src/nsSHistory.h
index d28fe7e5478..4bd252eb84c 100644
--- a/mozilla/docshell/shistory/src/nsSHistory.h
+++ b/mozilla/docshell/shistory/src/nsSHistory.h
@@ -76,9 +76,11 @@ public:
   // One time initialization method called upon docshell module construction
   static nsresult Startup();
 
-  // Calculates a max number of total
-  // content viewers to cache, based on amount of total memory
-  static PRUint32 GetMaxTotalViewers();
+  // Max number of total cached content viewers.  If the pref
+  // browser.sessionhistory.max_total_viewers is negative, then
+  // this value is calculated based on the total amount of memory.
+  // Otherwise, it comes straight from the pref.
+  static PRUint32 GetMaxTotalViewers() { return sHistoryMaxTotalViewers; }
 
 protected:
   virtual ~nsSHistory();
@@ -101,6 +103,10 @@ protected:
   static void EvictGlobalContentViewer();
   static void EvictAllContentViewers();
 
+  // Calculates a max number of total
+  // content viewers to cache, based on amount of total memory
+  static PRUint32 CalcMaxTotalViewers();
+
 protected:
   nsCOMPtr<nsISHTransaction> mListRoot;
   PRInt32 mIndex;