Bug 478927 - Add a new flag LOCATION_CHANGE_ERROR_PAGE for onLocationChangeBug. r=smaug, sr=bzbarsky

docshell/base/nsDocShell.cpp

@@ -7535,14 +7535,14 @@ nsDocShell::CreateContentViewer(const char *aContentType,
 
         // Create an shistory entry for the old load.
         if (failedURI) {
-#ifdef DEBUG
             bool errorOnLocationChangeNeeded =
-#endif
-            OnNewURI(failedURI, failedChannel, nsnull, mLoadType, true, false,
-                     false);
+                OnNewURI(failedURI, failedChannel, nsnull, mLoadType, false,
+                         false, false);
 
-            MOZ_ASSERT(!errorOnLocationChangeNeeded,
-                       "We have to fire onLocationChange again.");
+            if (errorOnLocationChangeNeeded) {
+                FireOnLocationChange(this, failedChannel, failedURI,
+                                     LOCATION_CHANGE_ERROR_PAGE);
+            }
         }
 
         // Be sure to have a correct mLSHE, it may have been cleared by

uriloader/base/nsIWebProgressListener.idl

@@ -309,8 +309,23 @@ interface nsIWebProgressListener : nsISupports
    *   This flag is on when |aWebProgress| did not load a new document. 
    *   For example, the location change is due to an anchor scroll or a
    *   pushState/popState/replaceState.
+   *
+   * LOCATION_CHANGE_ERROR_PAGE
+   *   This flag is on when |aWebProgress| redirected from the requested
+   *   contents to an internal page to show error status, such as
+   *   <about:neterror>, <about:certerror> and so on.
+   *
+   *   Generally speaking, |aURI| and |aRequest| are the original data. DOM
+   *   |window.location.href| is also the original location, while
+   *   |document.documentURI| is the redirected location. Sometimes |aURI| is
+   *   <about:blank> and |aRequest| is null when the original data does not
+   +   remain.
+   *
+   *   |aWebProgress| does NOT set this flag when it did not try to load a new
+   *   document. In this case, it should set LOCATION_CHANGE_SAME_DOCUMENT.
    */
   const unsigned long LOCATION_CHANGE_SAME_DOCUMENT   = 0x00000001;
+  const unsigned long LOCATION_CHANGE_ERROR_PAGE      = 0x00000002;
 
   /**
    * Called when the location of the window being watched changes.  This is not