Call WebStateObserver::DidStopLoading for native content reloads.

ios/web/web_state/ui/crw_web_controller.mm

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "ios/web/web_state/ui/crw_web_controller.h"
 
 #import <WebKit/WebKit.h>
 
 #import <objc/runtime.h>
 #include <stddef.h>
@@ skipping 2021 matching lines @@
   // implementation. This will be inaccurate if the reload fails or is
   // cancelled.
   _lastUserInteraction.reset();
   base::RecordAction(UserMetricsAction("Reload"));
   GURL url = self.currentNavItem->GetURL();
   if ([self shouldLoadURLInNativeView:url]) {
     std::unique_ptr<web::NavigationContextImpl> navigationContext = [self
         registerLoadRequestForURL:url
                          referrer:self.currentNavItemReferrer
                        transition:ui::PageTransition::PAGE_TRANSITION_RELOAD];
+    [self didStartLoadingURL:url];
     [self.nativeController reload];
     _webStateImpl->OnNavigationFinished(navigationContext.get());
     [self loadCompleteWithSuccess:YES forNavigation:nil];
   } else {
     web::NavigationItem* transientItem =
         self.navigationManagerImpl->GetTransientItem();
     if (transientItem) {
       // If there's a transient item, a reload is considered a new navigation to
       // the transient item's URL (as on other platforms).
       NavigationManager::WebLoadParams reloadParams(transientItem->GetURL());
@@ skipping 80 matching lines @@
 }
 
 - (void)loadCompleteWithSuccess:(BOOL)loadSuccess
                   forNavigation:(WKNavigation*)navigation {
   [self removePlaceholderOverlay];
   // The webView may have been torn down (or replaced by a native view). Be
   // safe and do nothing if that's happened.
   if (_loadPhase != web::PAGE_LOADING)
     return;
 
-  DCHECK(_webView);

[Eugene But (OOO till 7-30), 2017/05/26 17:36:32]

This is now called for native content

-
   const GURL currentURL([self currentURL]);
 
   _loadPhase = web::PAGE_LOADED;
 
   [self optOutScrollsToTopForSubviews];
 
   DCHECK((currentURL == _lastRegisteredRequestURL) ||  // latest navigation
          // previous navigation
          ![[_navigationStates lastAddedNavigation] isEqual:navigation] ||
          // invalid URL load
@@ skipping 3084 matching lines @@
 - (NSUInteger)observerCount {
   DCHECK_EQ(_observerBridges.size(), [_observers count]);
   return [_observers count];
 }
 
 - (NSString*)referrerFromNavigationAction:(WKNavigationAction*)action {
   return [action.request valueForHTTPHeaderField:kReferrerHeaderName];
 }
 
 @end