implement user agent override option.

ios/chrome/browser/tabs/tab_unittest.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 <UIKit/UIKit.h>
 
 #include <memory>
 
 #include "base/callback.h"
 #include "base/files/file_path.h"
@@ skipping 219 matching lines @@
     DCHECK_EQ(tab_.get().webState, web_state_impl_);
 
     [tab_ webWillAddPendingURL:userUrl transition:ui::PAGE_TRANSITION_TYPED];
     web_state_impl_->OnProvisionalNavigationStarted(userUrl);
     [tab_ webWillAddPendingURL:redirectUrl
                     transition:ui::PAGE_TRANSITION_CLIENT_REDIRECT];
 
     web::Referrer empty_referrer;
     [tab_ navigationManagerImpl]->AddPendingItem(
         redirectUrl, empty_referrer, ui::PAGE_TRANSITION_CLIENT_REDIRECT,
-        web::NavigationInitiationType::RENDERER_INITIATED);
+        web::NavigationInitiationType::RENDERER_INITIATED,
+        web::NavigationManager::UserAgentOverrideOption::INHERIT);
 
     web_state_impl_->OnProvisionalNavigationStarted(redirectUrl);
     [[tab_ navigationManagerImpl]->GetSessionController() commitPendingItem];
     [[tab_ webController] webStateImpl]->UpdateHttpResponseHeaders(redirectUrl);
     [[tab_ webController] webStateImpl]->OnNavigationCommitted(redirectUrl);
 
     base::string16 new_title = base::SysNSStringToUTF16(title);
     [tab_ navigationManager]->GetLastCommittedItem()->SetTitle(new_title);
 
     web_state_impl_->OnTitleChanged();
@@ skipping 300 matching lines @@
       [[FakeNativeAppMetadata alloc] init]);
 
   // Turn auto open on.
   [metadata setShouldAutoOpenLinks:YES];
   int expectedCallCount = 2;
   TestOpenNativeAppURL(testURL, NO, expectedCallCount, NO);
   EXPECT_FALSE([metadata shouldAutoOpenLinks]);
 }
 
 }  // namespace