--- a/docshell/base/nsDocShell.cpp
+++ b/docshell/base/nsDocShell.cpp
@@ -2410,22 +2410,16 @@ nsDocShell::SetItemType(PRInt32 aItemTyp
     
     NS_ENSURE_STATE(!mParent || mParent == docLoaderService);
 
     mItemType = aItemType;
 
     // disable auth prompting for anything but content
     mAllowAuth = mItemType == typeContent; 
 
-    nsRefPtr<nsPresContext> presContext = nsnull;
-    GetPresContext(getter_AddRefs(presContext));
-    if (presContext) {
-        presContext->UpdateIsChromeCache();
-    }
-
     return NS_OK;
 }
 
 NS_IMETHODIMP
 nsDocShell::GetParent(nsIDocShellTreeItem ** aParent)
 {
     if (!mParent) {
         *aParent = nsnull;

--- a/layout/base/nsPresContext.cpp
+++ b/layout/base/nsPresContext.cpp
@@ -1330,17 +1330,16 @@ nsPresContext::StopImagesFor(nsIFrame* a
 
 void
 nsPresContext::SetContainer(nsISupports* aHandler)
 {
   mContainer = do_GetWeakReference(aHandler);
   if (mContainer) {
     GetDocumentColorPreferences();
   }
-  UpdateIsChromeCacheInternal();
 }
 
 already_AddRefed<nsISupports>
 nsPresContext::GetContainerInternal() const
 {
   nsISupports *result = nsnull;
   if (mContainer)
     CallQueryReferent(mContainer.get(), &result);
@@ -1620,39 +1619,33 @@ void
 nsPresContext::CountReflows(const char * aName, nsIFrame * aFrame)
 {
   if (mShell) {
     mShell->CountReflows(aName, aFrame);
   }
 }
 #endif
 
-void
-nsPresContext::UpdateIsChromeCacheInternal()
+PRBool
+nsPresContext::IsChrome() const
 {
   PRBool isChrome = PR_FALSE;
   nsCOMPtr<nsISupports> container = GetContainer();
   if (container) {
     nsresult result;
     nsCOMPtr<nsIDocShellTreeItem> docShell(do_QueryInterface(container, &result));
     if (NS_SUCCEEDED(result) && docShell) {
       PRInt32 docShellType;
       result = docShell->GetItemType(&docShellType);
       if (NS_SUCCEEDED(result)) {
         isChrome = nsIDocShellTreeItem::typeChrome == docShellType;
       }
     }
   }
-  mIsChrome = isChrome;
-}
-
-void
-nsPresContext::UpdateIsChromeCacheExternal()
-{
-  UpdateIsChromeCacheInternal();
+  return isChrome;
 }
 
 /* virtual */ PRBool
 nsPresContext::HasAuthorSpecifiedRules(nsIFrame *aFrame, PRUint32 ruleTypeMask) const
 {
   return
     nsRuleNode::HasAuthorSpecifiedRules(aFrame->GetStyleContext(),
                                         ruleTypeMask,

--- a/layout/base/nsPresContext.h
+++ b/layout/base/nsPresContext.h
@@ -805,27 +805,17 @@ public:
   const nscoord* GetBorderWidthTable() { return mBorderWidthTable; }
 
   PRBool IsDynamic() { return (mType == eContext_PageLayout || mType == eContext_Galley); }
   PRBool IsScreen() { return (mMedium == nsGkAtoms::screen ||
                               mType == eContext_PageLayout ||
                               mType == eContext_PrintPreview); }
 
   // Is this presentation in a chrome docshell?
-  PRBool IsChrome() const { return mIsChrome; }
-
-  virtual void UpdateIsChromeCacheExternal();
-  void UpdateIsChromeCacheInternal();
-#ifdef _IMPL_NS_LAYOUT
-  void UpdateIsChromeCache()
-  { UpdateIsChromeCacheInternal(); }
-#else
-  void UpdateIsChromeCache()
-  { UpdateIsChromeCacheExternal(); }
-#endif
+  PRBool IsChrome() const;
 
   // Public API for native theme code to get style internals.
   virtual PRBool HasAuthorSpecifiedRules(nsIFrame *aFrame, PRUint32 ruleTypeMask) const;
 
   // Is it OK to let the page specify colors and backgrounds?
   PRBool UseDocumentColors() const {
     return GetCachedBoolPref(kPresContext_UseDocumentColors) || IsChrome();
   }
@@ -1120,19 +1110,16 @@ protected:
   // the document rather than to change the document's dimensions
   unsigned              mSupressResizeReflow : 1;
 
   unsigned              mIsVisual : 1;
 
   unsigned              mProcessingRestyles : 1;
   unsigned              mProcessingAnimationStyleChange : 1;
 
-  // Cache whether we are chrome or not because it is expensive.  
-  unsigned              mIsChrome : 1;
-
 #ifdef DEBUG
   PRBool                mInitialized;
 #endif
 
 
 protected:
 
   virtual ~nsPresContext() NS_HIDDEN;