(Set)IsOverridingUserAgent should be called on VisibleItem

ios/web/web_state/ui/crw_web_controller.mm

Index: ios/web/web_state/ui/crw_web_controller.mm
diff --git a/ios/web/web_state/ui/crw_web_controller.mm b/ios/web/web_state/ui/crw_web_controller.mm
index 9be54a339178bdd4e335334a41159a6f5b187d8e..dddf7a5c0a26f7cf16ec45dbbc3725293627161f 100644
--- a/ios/web/web_state/ui/crw_web_controller.mm
+++ b/ios/web/web_state/ui/crw_web_controller.mm
@@ -458,9 +458,6 @@ @interface CRWWebController ()<CRWContextMenuDelegate,
 
 // Returns YES if the user interacted with the page recently.
 @property(nonatomic, readonly) BOOL userClickedRecently;
-// Returns whether the desktop user agent should be used when setting the user
-// agent.
-@property(nonatomic, readonly) BOOL useDesktopUserAgent;
 
 // Facade for Mojo API.
 @property(nonatomic, readonly) web::MojoFacade* mojoFacade;
@@ -2331,11 +2328,6 @@ - (BOOL)shouldClosePageOnNativeApplicationLoad {
   return rendererInitiatedWithoutInteraction || noNavigationItems;
 }
 
-- (BOOL)useDesktopUserAgent {
-  web::NavigationItem* item = [self currentNavItem];
-  return item && item->IsOverridingUserAgent();
-}
-
 - (web::MojoFacade*)mojoFacade {
   if (!_mojoFacade) {
     service_manager::mojom::InterfaceProvider* interfaceProvider =
@@ -4204,9 +4196,9 @@ - (void)ensureWebViewCreatedWithConfiguration:(WKWebViewConfiguration*)config {
 - (WKWebView*)webViewWithConfiguration:(WKWebViewConfiguration*)config {
   // Do not attach the context menu controller immediately as the JavaScript
   // delegate must be specified.
-  return web::BuildWKWebView(CGRectZero, config,
-                             self.webStateImpl->GetBrowserState(),
-                             [self useDesktopUserAgent]);
+  return web::BuildWKWebView(
+      CGRectZero, config, self.webStateImpl->GetBrowserState(),
+      self.navigationManagerImpl->IsUsingDesktopUserAgent());

[Eugene But (OOO till 7-30), 2017/02/22 21:57:42]

Is it guaranteed that |self.navigationManagerImpl| never returns null here?

[liaoyuke, 2017/02/22 23:48:31]

Good catch!

 }
 
 - (void)setWebView:(WKWebView*)webView {