Implement Reload for ORIGINAL_REQUEST_URL in NavigationManagerImpl.

ios/web/navigation/navigation_manager_impl.mm

 // Copyright 2013 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/navigation/navigation_manager_impl.h"
 
 #include <stddef.h>
 
 #include <utility>
 
@@ skipping 321 matching lines @@
 NavigationItemList NavigationManagerImpl::GetBackwardItems() const {
   return [session_controller_ backwardItems];
 }
 
 NavigationItemList NavigationManagerImpl::GetForwardItems() const {
   return [session_controller_ forwardItems];
 }
 
 void NavigationManagerImpl::Reload(ReloadType reload_type,
                                    bool check_for_reposts) {
+  // Reload with ORIGINAL_REQUEST_URL type should reload with the original
+  // request url of the current item because a server side redirect may change

[Eugene But (OOO till 7-30), 2017/03/27 17:15:47]

Could you please avoid referring to "current item". Chrome has multiple ways to
implement "current item" and this term is quite confusing.

[liaoyuke, 2017/03/28 00:16:40]

Done.

+  // its url. For example, an user visits www.youtube.com and is then redirected

[Eugene But (OOO till 7-30), 2017/03/27 17:15:47]

nit: s/www.youtube.com/www.chromium.org and s/m.youtube.com/m.chromium.org

[liaoyuke, 2017/03/28 00:16:40]

Done.

+  // to m.youtube.com, when the user wants to refresh the page with a different
+  // configuration (e.g. user agent), the user would be expecting to visit
+  // www.youtube.com instead of m.youtube.com.
+  // NOTE: this logic has the following two assumptions:
+  // 1. |-reload| in web controller always reloads the current item.
+  // 2. Generally, a website would not issue a client side redirect
+  //    (e.g. window.location) to redirect an user to its mobile version.
+  if (reload_type == web::ReloadType::ORIGINAL_REQUEST_URL) {
+    NavigationItem* current_item = [session_controller_ currentItem];

[Eugene But (OOO till 7-30), 2017/03/27 17:15:47]

The end goal is to remove |currentItem|, so it will be better to avoid adding
new calls fro this API. According to ReloadType::ORIGINAL_REQUEST_URL this code
should reload visible item, so maybe s/currentItem/visibleItem?

[liaoyuke, 2017/03/28 00:16:40]

Addressed per offline discussion.

+    DCHECK(current_item);
+    current_item->SetURL(current_item->GetOriginalRequestURL());

[Eugene But (OOO till 7-30), 2017/03/27 17:15:47]

Should we crash if NM is empty? Does this code crash for ReloadType::NORMAL
reload?

[liaoyuke, 2017/03/28 00:16:40]

This function should do nothing if NM is empty. Addressed in a separate CL.

+  }
+
   delegate_->Reload();
 }
 
 void NavigationManagerImpl::CopyStateFromAndPrune(
     const NavigationManager* manager) {
   DCHECK(manager);
   CRWSessionController* other_session =
       static_cast<const NavigationManagerImpl*>(manager)->session_controller_;
   [session_controller_ copyStateFromSessionControllerAndPrune:other_session];
 }
@@ skipping 75 matching lines @@
     // The desktop user agent cannot be used for a pending navigation to an
     // app-specific URL.
     DCHECK_NE(pending_item->GetUserAgentType(), UserAgentType::NONE);
     pending_item->SetUserAgentType(UserAgentType::DESKTOP);
   } else {
     override_desktop_user_agent_for_next_pending_item_ = true;
   }
 }
 
 bool NavigationManagerImpl::IsRedirectItemAtIndex(int index) const {
-  DCHECK_GT(index, 0);
+  DCHECK_GE(index, 0);
   DCHECK_LT(index, GetItemCount());
   ui::PageTransition transition = GetItemAtIndex(index)->GetTransitionType();
   return transition & ui::PAGE_TRANSITION_IS_REDIRECT_MASK;
 }
 
 NavigationItem* NavigationManagerImpl::GetLastCommittedNonAppSpecificItem()
     const {
   int index = GetLastCommittedItemIndex();
   if (index == -1)
     return nullptr;
   WebClient* client = GetWebClient();
   const ScopedNavigationItemImplList& items = [session_controller_ items];
   while (index >= 0) {
     NavigationItem* item = items[index--].get();
     if (!client->IsAppSpecificURL(item->GetVirtualURL()))
       return item;
   }
   return nullptr;
 }
 
 }  // namespace web