Always set the navigation pending item for page reload.

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 1503 matching lines @@
     [self recordStateInHistory];
   }
 
   [_delegate webWillAddPendingURL:requestURL transition:transition];
   // Add or update pending url.
   if (self.navigationManagerImpl->GetPendingItem()) {
     // Update the existing pending entry.
     // Typically on PAGE_TRANSITION_CLIENT_REDIRECT.
     [[self sessionController] updatePendingItem:requestURL];
   } else {
-    // A new session history entry needs to be created.
-    self.navigationManagerImpl->AddPendingItem(
-        requestURL, referrer, transition,
-        web::NavigationInitiationType::RENDERER_INITIATED,
-        web::NavigationManager::UserAgentOverrideOption::INHERIT);
+    // If this is a reload then there no need to create a new pending item,
+    // instead update the pending item to the last committed item.
+    if (PageTransitionCoreTypeIs(transition, ui::PAGE_TRANSITION_RELOAD)) {
+      self.sessionController.pendingItemIndex =
+          self.sessionController.lastCommittedItemIndex;
+    } else {
+      // A new session history entry needs to be created.
+      self.navigationManagerImpl->AddPendingItem(
+          requestURL, referrer, transition,
+          web::NavigationInitiationType::RENDERER_INITIATED,
+          web::NavigationManager::UserAgentOverrideOption::INHERIT);
+    }
   }
   std::unique_ptr<web::NavigationContextImpl> context =
       web::NavigationContextImpl::CreateNavigationContext(
           _webStateImpl, requestURL, transition);
 
   web::NavigationItem* item = self.navigationManagerImpl->GetPendingItem();
   // TODO(crbug.com/676129): AddPendingItem does not always create a pending
   // item. Remove this workaround once the bug is fixed.
   if (!item) {
     item = self.navigationManagerImpl->GetLastCommittedItem();
@@ skipping 442 matching lines @@
       [_containerView setAccessibilityIdentifier:@"Container View"];
 
     [_containerView addGestureRecognizer:[self touchTrackingRecognizer]];
     // Is |currentUrl| a web scheme or native chrome scheme.
     web::NavigationItem* item = self.currentNavItem;
     const GURL currentNavigationURL =
         item ? item->GetVirtualURL() : GURL::EmptyGURL();
     BOOL isChromeScheme =
         web::GetWebClient()->IsAppSpecificURL(currentNavigationURL);
 
+    // Since this is implicit reload, no new pending item should be created, set
+    // the pending item index to the last committed item.
+    self.sessionController.pendingItemIndex =
+        self.sessionController.lastCommittedItemIndex;
+
     // Don't immediately load the web page if in overlay mode. Always load if
     // native.
     if (isChromeScheme || !_overlayPreviewMode) {
       // TODO(jimblackler): end the practice of calling |loadCurrentURL| when it
       // is possible there is no current URL. If the call performs necessary
       // initialization, break that out.
       [self loadCurrentURL];
     }
 
     // Display overlay view until current url has finished loading or delay and
@@ skipping 21 matching lines @@
 }
 
 - (void)reload {
   // Clear last user interaction.
   // TODO(crbug.com/546337): Move to after the load commits, in the subclass
   // implementation. This will be inaccurate if the reload fails or is
   // cancelled.
   _lastUserInteraction.reset();
   base::RecordAction(UserMetricsAction("Reload"));
   GURL url = self.currentNavItem->GetURL();
+  // Reloading shouldn't create create a new pending item, instead set the
+  // pending item index to the last committed item.
+  self.sessionController.pendingItemIndex =

[Eugene But (OOO till 7-30), 2017/06/15 00:08:11]

Wouldn't |reload| eventually call |registerLoadRequestForURL:| which also sets
pendingItemIndex? Or this code is really necessary?

[mrefaat, 2017/06/15 18:35:35]

This will not happen in every case, only when the the url is going to be open
natively not on web view.
I can move setting the pending item open in webview condition but i think this
is much simpler and easier to understand.

[Eugene But (OOO till 7-30), 2017/06/16 03:25:46]

Thanks. So this code is needed to cover NativeContent reload. 

But then how could it happen that Line 1527 can execute (Reload Transition and
no pending item)? 

[mrefaat, 2017/06/16 19:28:04]

This will happen in case the reload is triggered by the content itself not by
the browser.

[Eugene But (OOO till 7-30), 2017/06/17 02:57:14]

But reload triggered by renderer calls |reload| as well:
https://cs.chromium.org/chromium/src/ios/web/web_state/ui/crw_web_controller....

Did I miss something?

[mrefaat, 2017/06/17 11:33:08]

I'm not sure, from what i see it seems that goDelta is only called for history
forward/backward. and during my tests i have not passed through this function
once.

+      self.sessionController.lastCommittedItemIndex;
   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 {
@@ skipping 3190 matching lines @@
 - (NSUInteger)observerCount {
   DCHECK_EQ(_observerBridges.size(), [_observers count]);
   return [_observers count];
 }
 
 - (NSString*)referrerFromNavigationAction:(WKNavigationAction*)action {
   return [action.request valueForHTTPHeaderField:kReferrerHeaderName];
 }
 
 @end