Bug 293714. Be smart about guessing whether a vertical scrollbar is needed when we do the first real reflow of a scrollframe; remember in global history whether the page needed a scrollbar or not. r+sr=bzbarsky

git-svn-id: svn://10.0.0.236/trunk@178883 18797224-902f-48f8-a5cc-f745e15eee43

mozilla/docshell/base/nsGlobalHistoryAdapter.cpp

@@ -197,3 +197,15 @@ nsGlobalHistoryAdapter::SetPageTitle(nsIURI* aURI, const nsAString& aTitle)
 {
   return NS_ERROR_NOT_IMPLEMENTED;
 }
+
+NS_IMETHODIMP
+nsGlobalHistoryAdapter::SetURIGeckoFlags(nsIURI *aURI, PRUint32 aFlags)
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsGlobalHistoryAdapter::GetURIGeckoFlags(nsIURI *aURI, PRUint32* aFlags)
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}

mozilla/docshell/base/nsIGlobalHistory2.idl

@@ -51,9 +51,12 @@ interface nsIURI;
 // the nsIURI is the subject
 #define NS_LINK_VISITED_EVENT_TOPIC "link-visited"
 
+// This is NOT part of the interface! It could change.
+#define NS_GECKO_FLAG_NEEDS_VERTICAL_SCROLLBAR (1 << 0)
+
 %}
 
-[scriptable, uuid(cf777d42-1270-4b34-be7b-2931c93feda5)]
+[scriptable, uuid(fbcfa5ca-5d05-4726-b325-d0e6563a1715)]
 interface nsIGlobalHistory2 : nsISupports
 {
     /**
@@ -89,4 +92,17 @@ interface nsIGlobalHistory2 : nsISupports
      * @param aTitle  the page title
      */
     void setPageTitle(in nsIURI aURI, in AString aTitle);
+
+    /**
+     * Get the Gecko flags for this URI. These flags are used by Gecko as hints
+     * to optimize page loading. Not all histories have them; this need not be
+     * supported (just return NS_ERROR_NOT_IMPLEMENTED. These flags are opaque
+     * and should not be interpreted by the history engine.
+     */
+    unsigned long getURIGeckoFlags(in nsIURI aURI);
+    /**
+     * Set the Gecko flags for this URI. May fail if the history entry
+     * doesn't have any flags or if there is no entry for the URI.
+     */
+    void setURIGeckoFlags(in nsIURI aURI, in unsigned long aFlags);
 };