Implement Reload for ORIGINAL_REQUEST_URL in NavigationManagerImpl.

ios/web/navigation/navigation_manager_impl.mm

Index: ios/web/navigation/navigation_manager_impl.mm
diff --git a/ios/web/navigation/navigation_manager_impl.mm b/ios/web/navigation/navigation_manager_impl.mm
index a059c1d0e3c19f4421442ccc06de66ddcc44dd38..537aab0a0e9b7f87ff56819713cdb270321f932c 100644
--- a/ios/web/navigation/navigation_manager_impl.mm
+++ b/ios/web/navigation/navigation_manager_impl.mm
@@ -339,6 +339,22 @@ bool AreURLsInPageNavigation(const GURL& existing_url, const GURL& new_url) {
 
 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();
 }
 
@@ -434,7 +450,7 @@ bool AreURLsInPageNavigation(const GURL& existing_url, const GURL& new_url) {
 }
 
 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;