[Bug] Switch GetLastCommittedNonAppSpecificItem to use non-virtual URL.

Currently there is an inconsistency between CreateNavigationItem and
GetLastCommittedNonAppSpecificItem. The former sets user agent type of
an item to NONE if URL is app-specific. The latter looks for an item
with user agent type that is not NONE, and uses VirtualURL to find
these. Historically this has not been a problem because app-specific
URLs always had identical VirtualURL.

Offline Reading List navigation items break this assumption. They have
app-specific URLs (e.g. chrome://offline/<blob>) and regular-looking
VirtualURLs.

Bug: 781284
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I45d9afdb854b1d5340f6d4d2bb7ac306f0897662
Reviewed-on: https://chromium-review.googlesource.com/764540
Commit-Queue: Danyao Wang <danyao@chromium.org>
Reviewed-by: Eugene But <eugenebut@chromium.org>
Reviewed-by: Yuke Liao <liaoyuke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#515983}

ios/web/navigation/navigation_manager_impl.mm

@@ -355,7 +355,7 @@ NavigationItem* NavigationManagerImpl::GetLastCommittedNonAppSpecificItem()
   WebClient* client = GetWebClient();
   for (int index = GetLastCommittedItemIndex(); index >= 0; index--) {
     NavigationItem* item = GetItemAtIndex(index);
-    if (!client->IsAppSpecificURL(item->GetVirtualURL()))
+    if (!client->IsAppSpecificURL(item->GetURL()))
       return item;
   }
   return nullptr;

ios/web/navigation/navigation_manager_impl_unittest.mm

@@ -1363,6 +1363,9 @@ TEST_P(NavigationManagerTest, UserAgentTypePropagationPastNativeItems) {
 
   web::NavigationItem* native_item1 =
       navigation_manager()->GetLastCommittedItem();
+  // Having a non-app-specific URL should not change the fact that the native
+  // item should be skipped when determining user agent inheritance.
+  native_item1->SetVirtualURL(GURL("http://non-app-specific-url"));
   ASSERT_EQ(web::UserAgentType::NONE, native_item1->GetUserAgentType());
   navigation_manager()->AddPendingItem(
       GURL("http://www.2.com"), Referrer(), ui::PAGE_TRANSITION_TYPED,