Create new pending item if UserAgentOverrideOption is not INHERIT.

ios/web/navigation/crw_session_controller.mm

Index: ios/web/navigation/crw_session_controller.mm
diff --git a/ios/web/navigation/crw_session_controller.mm b/ios/web/navigation/crw_session_controller.mm
index 292d9fc3eb2275fe8fe977f737e694619c28b546..4434bd99627dd7ee995d7093af760716963c7e5a 100644
--- a/ios/web/navigation/crw_session_controller.mm
+++ b/ios/web/navigation/crw_session_controller.mm
@@ -282,9 +282,11 @@ - (void)setBrowserState:(web::BrowserState*)browserState {
 }
 
 - (void)addPendingItem:(const GURL&)url
-              referrer:(const web::Referrer&)ref
-            transition:(ui::PageTransition)trans
-        initiationType:(web::NavigationInitiationType)initiationType {
+                   referrer:(const web::Referrer&)ref
+                 transition:(ui::PageTransition)trans
+             initiationType:(web::NavigationInitiationType)initiationType
+    userAgentOverrideOption:(web::NavigationManager::UserAgentOverrideOption)
+                                userAgentOverrideOption {
   // Server side redirects are handled by updating existing pending item instead
   // of adding a new item.
   DCHECK((trans & ui::PAGE_TRANSITION_SERVER_REDIRECT) == 0);
@@ -312,6 +314,10 @@ - (void)addPendingItem:(const GURL&)url
         !hasSameURL ||
         (isPendingTransitionFormSubmit && !isCurrentTransitionFormSubmit);
 
+    if (userAgentOverrideOption !=
+        web::NavigationManager::UserAgentOverrideOption::INHERIT)

[kkhorimoto, 2017/04/05 23:01:44]

I think we should also check whether the override option differs from the
current item's UA type so that we don't create new items that end up having the
same UA type as the previous item.  Also, can we define a separate bool after
|isCurrentTransitionFormSumbit| that checks this logic, then include it in the
|| statment where we define |shouldCreatePendingItem|?

[liaoyuke, 2017/04/06 22:24:55]

Theoretically, override option should always be different from current item's UI
type, so adding a DCHECK.

+      shouldCreatePendingItem = YES;
+
     if (!shouldCreatePendingItem) {
       // Send the notification anyway, to preserve old behavior. It's unknown
       // whether anything currently relies on this, but since both this whole