(Set)IsOverridingUserAgent should be called on VisibleItem

ios/web/web_state/ui/crw_web_controller.mm

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "ios/web/web_state/ui/crw_web_controller.h"
 
 #import <WebKit/WebKit.h>
 
 #import <objc/runtime.h>
 #include <stddef.h>
@@ skipping 440 matching lines @@
 // This method can change the state of the CRWWebController, as it will display
 // an error if the returned URL is not reliable from a security point of view.
 // Note that this method is expensive, so it should always be cached locally if
 // it's needed multiple times in a method.
 @property(nonatomic, readonly) GURL currentURL;
 // Returns the referrer for the current page.
 @property(nonatomic, readonly) web::Referrer currentReferrer;
 
 // 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;
 
 // Updates Desktop User Agent and calls webWillFinishHistoryNavigationFromEntry:
 // on CRWWebDelegate. TODO(crbug.com/684098): Remove this method and inline its
 // content.
 - (void)webWillFinishHistoryNavigationFromEntry:(CRWSessionEntry*)fromEntry;
 // Recreates web view if |entry| and |fromEntry| have different value for
 // IsOverridingUserAgent() flag.
@@ skipping 1850 matching lines @@
   // The page should be closed if it was initiated by the DOM and there has been
   // no user interaction with the page since the web view was created, or if
   // the page has no navigation items, as occurs when an App Store link is
   // opened from another application.
   BOOL rendererInitiatedWithoutInteraction =
       self.sessionController.openedByDOM && !_userInteractedWithWebController;
   BOOL noNavigationItems = !(self.navigationManagerImpl->GetItemCount());
   return rendererInitiatedWithoutInteraction || noNavigationItems;
 }
 
-- (BOOL)useDesktopUserAgent {
-  web::NavigationItem* item = [self currentNavItem];
-  return item && item->IsOverridingUserAgent();
-}
-
 - (web::MojoFacade*)mojoFacade {
   if (!_mojoFacade) {
     service_manager::mojom::InterfaceProvider* interfaceProvider =
         _webStateImpl->GetMojoInterfaceRegistry();
     _mojoFacade.reset(new web::MojoFacade(interfaceProvider, self));
   }
   return _mojoFacade.get();
 }
 
 - (CRWPassKitDownloader*)passKitDownloader {
@@ skipping 1848 matching lines @@
     base::scoped_nsobject<CRWWebViewContentView> webViewContentView(
         [[CRWWebViewContentView alloc] initWithWebView:_webView
                                             scrollView:self.webScrollView]);
     [_containerView displayWebViewContentView:webViewContentView];
   }
 }
 
 - (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 {
   DCHECK_NE(_webView.get(), webView);
 
   // Unwind the old web view.
   // TODO(eugenebut): Remove CRWWKScriptMessageRouter once crbug.com/543374 is
   // fixed.
   CRWWKScriptMessageRouter* messageRouter =
       [self webViewConfigurationProvider].GetScriptMessageRouter();
@@ skipping 1011 matching lines @@
 - (void)simulateLoadRequestWithURL:(const GURL&)URL {
   _lastRegisteredRequestURL = URL;
   _loadPhase = web::LOAD_REQUESTED;
 }
 
 - (NSString*)referrerFromNavigationAction:(WKNavigationAction*)action {
   return [action.request valueForHTTPHeaderField:kReferrerHeaderName];
 }
 
 @end