Reload offline version on load failure

ios/web/web_state/ui/crw_web_controller.mm

Index: ios/web/web_state/ui/crw_web_controller.mm
diff --git a/ios/web/web_state/ui/crw_web_controller.mm b/ios/web/web_state/ui/crw_web_controller.mm
index ca23114424b25110cd961183512fc18ee9f53b60..1bc7e98233a3f3d07e66d71c0aface89b0da87e7 100644
--- a/ios/web/web_state/ui/crw_web_controller.mm
+++ b/ios/web/web_state/ui/crw_web_controller.mm
@@ -3476,6 +3476,26 @@ const NSTimeInterval kSnapshotOverlayTransition = 0.5;
   return YES;
 }
 
+- (void)displayOfflineVersionForURL:(const GURL&)URL {
+  if ([_nativeProvider hasControllerForURL:URL]) {
+    id<CRWNativeContent> controller = [_nativeProvider controllerForURL:URL];
+    web::NavigationItem* item =
+        self.webState->GetNavigationManager()->GetItemAtIndex(
+            self.webState->GetNavigationManager()->GetCurrentItemIndex());
+    // Allows the native content to set the displayed URL.
+    if (item) {
+      item->SetURL([controller url]);
+      if ([controller respondsToSelector:@selector(virtualURL)]) {
+        item->SetVirtualURL([controller virtualURL]);
+      }
+    }
+    [self loadCompleteWithSuccess:NO];
+    [self removeWebViewAllowingCachedReconstruction:NO];
+    [self setNativeController:controller];
+    [self loadNativeViewWithSuccess:YES];
+  }
+}
+
 - (void)handleLoadError:(NSError*)error inMainFrame:(BOOL)inMainFrame {
   NSString* MIMEType = [_pendingNavigationInfo MIMEType];
   if ([_passKitDownloader isMIMETypePassKitType:MIMEType])