Fix transition type for same-document back forward navigations.

This change keeps the original transition type and adds
PAGE_TRANSITION_FORWARD_BACK as qualifier.

Change-Id: Ia3b59c3d555223a66a5553cbba2ff1ebf3b28f0c
Reviewed-on: https://chromium-review.googlesource.com/c/1371883Reviewed-by: Danyao Wang <danyao@chromium.org>
Commit-Queue: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#615817}

ios/web/web_state/ui/crw_web_controller.mm

@@ -4974,11 +4974,15 @@ registerLoadRequestForURL:(const GURL&)requestURL
 - (void)didFinishGoToIndexSameDocumentNavigationWithType:
             (web::NavigationInitiationType)type
                                           hasUserGesture:(BOOL)hasUserGesture {
-  GURL URL = _webStateImpl->GetLastCommittedURL();
+  web::NavigationItem* item =
+      _webStateImpl->GetNavigationManager()->GetLastCommittedItem();
+  GURL URL = item->GetVirtualURL();
   std::unique_ptr<web::NavigationContextImpl> context =
       web::NavigationContextImpl::CreateNavigationContext(
           _webStateImpl, URL, hasUserGesture,
-          ui::PageTransition::PAGE_TRANSITION_FORWARD_BACK,
+          static_cast<ui::PageTransition>(
+              item->GetTransitionType() |
+              ui::PageTransition::PAGE_TRANSITION_FORWARD_BACK),
           type == web::NavigationInitiationType::RENDERER_INITIATED);
   context->SetIsSameDocument(true);
   _webStateImpl->SetIsLoading(true);

ios/web/web_state/web_state_observer_inttest.mm

@@ -1013,8 +1013,9 @@ TEST_P(WebStateObserverTest, UserInitiatedHashChangeNavigation) {
   EXPECT_CALL(observer_, DidStartLoading(web_state()));
 
   bool has_user_gesture = true;
-  ui::PageTransition expected_transition =
-      ui::PageTransition::PAGE_TRANSITION_FORWARD_BACK;
+  ui::PageTransition expected_transition = static_cast<ui::PageTransition>(
+      ui::PageTransition::PAGE_TRANSITION_FORWARD_BACK |
+      ui::PageTransition::PAGE_TRANSITION_TYPED);
   if (GetWebClient()->IsSlimNavigationManagerEnabled()) {
     // TODO(crbug.com/913052): propagate |has_user_gesture| on back/forward
     // navigation in slim nav.