Bug 553359. Cache whether the PresContext is chrome or not. r=bzbarsky

docshell/base/nsDocShell.cpp

@@ -2415,6 +2415,12 @@ nsDocShell::SetItemType(PRInt32 aItemType)
     // disable auth prompting for anything but content
     mAllowAuth = mItemType == typeContent; 
 
+    nsRefPtr<nsPresContext> presContext = nsnull;
+    GetPresContext(getter_AddRefs(presContext));
+    if (presContext) {
+        presContext->InvalidateIsChromeCache();
+    }
+
     return NS_OK;
 }
 

layout/base/nsPresContext.cpp

@@ -1332,6 +1332,7 @@ void
 nsPresContext::SetContainer(nsISupports* aHandler)
 {
   mContainer = do_GetWeakReference(aHandler);
+  mIsChromeIsCached = PR_FALSE;
   if (mContainer) {
     GetDocumentColorPreferences();
   }
@@ -1646,7 +1647,7 @@ nsPresContext::CountReflows(const char * aName, nsIFrame * aFrame)
 #endif
 
 PRBool
-nsPresContext::IsChrome() const
+nsPresContext::IsChromeSlow()
 {
   PRBool isChrome = PR_FALSE;
   nsCOMPtr<nsISupports> container = GetContainer();
@@ -1661,11 +1662,25 @@ nsPresContext::IsChrome() const
       }
     }
   }
-  return isChrome;
+  mIsChrome = isChrome;
+  mIsChromeIsCached = PR_TRUE;
+  return mIsChrome;
+}
+
+void
+nsPresContext::InvalidateIsChromeCacheInternal()
+{
+  mIsChromeIsCached = PR_FALSE;
+}
+
+void
+nsPresContext::InvalidateIsChromeCacheExternal()
+{
+  InvalidateIsChromeCacheInternal();
 }
 
 /* virtual */ PRBool
-nsPresContext::HasAuthorSpecifiedRules(nsIFrame *aFrame, PRUint32 ruleTypeMask) const
+nsPresContext::HasAuthorSpecifiedRules(nsIFrame *aFrame, PRUint32 ruleTypeMask)
 {
   return
     nsRuleNode::HasAuthorSpecifiedRules(aFrame->GetStyleContext(),

layout/base/nsPresContext.h

@@ -810,13 +810,26 @@ public:
                               mType == eContext_PrintPreview); }
 
   // Is this presentation in a chrome docshell?
-  PRBool IsChrome() const;
+  PRBool IsChrome()
+  {
+    return mIsChromeIsCached ? mIsChrome : IsChromeSlow();
+  }
+
+  virtual void InvalidateIsChromeCacheExternal();
+  void InvalidateIsChromeCacheInternal();
+#ifdef _IMPL_NS_LAYOUT
+  void InvalidateIsChromeCache()
+  { InvalidateIsChromeCacheInternal(); }
+#else
+  void InvalidateIsChromeCache()
+  { InvalidateIsChromeCacheExternal(); }
+#endif
 
   // Public API for native theme code to get style internals.
-  virtual PRBool HasAuthorSpecifiedRules(nsIFrame *aFrame, PRUint32 ruleTypeMask) const;
+  virtual PRBool HasAuthorSpecifiedRules(nsIFrame *aFrame, PRUint32 ruleTypeMask);
 
   // Is it OK to let the page specify colors and backgrounds?
-  PRBool UseDocumentColors() const {
+  PRBool UseDocumentColors() {
     return GetCachedBoolPref(kPresContext_UseDocumentColors) || IsChrome();
   }
 
@@ -980,6 +993,8 @@ protected:
   // Can't be inline because we can't include nsStyleSet.h.
   PRBool HasCachedStyleData();
 
+  PRBool IsChromeSlow();
+
   // IMPORTANT: The ownership implicit in the following member variables
   // has been explicitly checked.  If you add any members to this class,
   // please make the ownership explicit (pinkerton, scc).
@@ -1115,6 +1130,12 @@ protected:
   unsigned              mProcessingRestyles : 1;
   unsigned              mProcessingAnimationStyleChange : 1;
 
+  // Cache whether we are chrome or not because it is expensive.  
+  // mIsChromeIsCached tells us if mIsChrome is valid or we need to get the
+  // value the slow way.
+  unsigned              mIsChromeIsCached : 1;
+  unsigned              mIsChrome : 1;
+
 #ifdef DEBUG
   PRBool                mInitialized;
 #endif