[iOS] Fix document URL updates on error page reload

This CL makes sure that the documentURL is correctly updated, or is not
updated when the user is reloading an error page with the new workflow.

Bug: 1139303
Change-Id: I11d5f70eeb58077c0ed40f0b183c3f762f749ab8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2514205
Commit-Queue: Gauthier Ambard <gambard@chromium.org>
Reviewed-by: Ali Juma <ajuma@chromium.org>
Cr-Commit-Position: refs/heads/master@{#823485}

ios/web/navigation/crw_web_view_navigation_observer.mm

@@ -15,6 +15,7 @@
 #import "ios/web/navigation/crw_web_view_navigation_observer_delegate.h"
 #import "ios/web/navigation/crw_wk_navigation_handler.h"
 #import "ios/web/navigation/crw_wk_navigation_states.h"
+#import "ios/web/navigation/error_page_helper.h"
 #import "ios/web/navigation/navigation_context_impl.h"
 #import "ios/web/navigation/wk_navigation_util.h"
 #import "ios/web/public/web_client.h"
@@ -247,8 +248,9 @@ using web::wk_navigation_util::IsPlaceholderUrl;
   // 4) When a SafeBrowsing warning is displayed after
   //    decidePolicyForNavigationAction but before a provisional navigation
   //    starts, and the user clicks the "Go Back" link on the warning page.
+  // 5) When the user is reloading an error page.
   //
-  // If |isLoading| is NO, then it must be case 2, 3, or 4. If the last
+  // If |isLoading| is NO, then it must be case 2, 3, 4 or 5. If the last
   // committed URL (_documentURL) matches the current URL, assume that it is
   // case 4 if a SafeBrowsing warning is currently displayed and case 3
   // otherwise. If the URL does not match, assume it is a non-document-changing
@@ -266,6 +268,12 @@ using web::wk_navigation_util::IsPlaceholderUrl;
   // window.location.href will match the previous URL at this stage, not the web
   // view's current URL.
   if (!self.webView.loading) {
+    if ([ErrorPageHelper isErrorPageFileURL:URL] &&
+        self.documentURL ==
+            [ErrorPageHelper failedNavigationURLFromErrorPageFileURL:URL]) {
+      // Case 5: reloading an error page.
+      return;
+    }
     if (self.documentURL == URL) {
       if (!web::IsSafeBrowsingWarningDisplayedInWebView(self.webView))
         return;

ios/web/navigation/crw_wk_navigation_handler.mm

@@ -1002,7 +1002,7 @@ void ReportOutOfSyncURLInDidStartProvisionalNavigation(
   // webView has the file URL.
   BOOL isErrorPage =
       base::FeatureList::IsEnabled(web::features::kUseJSForErrorPage) &&
-      context && context->IsLoadingErrorPage();
+      [ErrorPageHelper isErrorPageFileURL:webViewURL];
 
   // When loading an error page that is a placeholder (legacy), the webViewURL
   // should be used as it is the actual URL we want to load.