Revert of Cleaned up old navigation code that did not use pending navigation item.

ios/chrome/browser/experimental_flags.mm

 // Copyright 2015 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.
 
 // This file can be empty. Its purpose is to contain the relatively short lived
 // definitions required for experimental flags.
 
 #include "ios/chrome/browser/experimental_flags.h"
 
 #include <dispatch/dispatch.h>
@@ skipping 23 matching lines @@
 NSString* const kEnableStartupCrash = @"EnableStartupCrash";
 NSString* const kEnableViewCopyPasswords = @"EnableViewCopyPasswords";
 NSString* const kExternalAppPromptDisabled = @"ExternalAppPromptDisabled";
 NSString* const kFirstRunForceEnabled = @"FirstRunForceEnabled";
 NSString* const kForceResetContextualSearch = @"ForceResetContextualSearch";
 NSString* const kGaiaEnvironment = @"GAIAEnvironment";
 NSString* const kHeuristicsForPasswordGeneration =
     @"HeuristicsForPasswordGeneration";
 NSString* const kMDMIntegrationDisabled = @"MDMIntegrationDisabled";
 NSString* const kOriginServerHost = @"AlternateOriginServerHost";
+NSString* const kPendingIndexNavigationDisabled =
+    @"PendingIndexNavigationDisabled";
 NSString* const kSafariVCSignInDisabled = @"SafariVCSignInDisabled";
 NSString* const kWhatsNewPromoStatus = @"WhatsNewPromoStatus";
 
 const base::Feature kIOSDownloadImageRenaming{
     "IOSDownloadImageRenaming", base::FEATURE_DISABLED_BY_DEFAULT};
 
 }  // namespace
 
 namespace experimental_flags {
 
@@ skipping 138 matching lines @@
     return true;
   } else if (command_line->HasSwitch(switches::kDisablePaymentRequest)) {
     return false;
   }
 
   // Check if the Finch experiment is turned on.
   return base::StartsWith(group_name, "Enabled",
                           base::CompareCase::INSENSITIVE_ASCII);
 }
 
+bool IsPendingIndexNavigationEnabled() {
+  return ![[NSUserDefaults standardUserDefaults]
+      boolForKey:kPendingIndexNavigationDisabled];
+}
+
 bool IsPhysicalWebEnabled() {
   base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
   if (command_line->HasSwitch(switches::kEnableIOSPhysicalWeb)) {
     return true;
   } else if (command_line->HasSwitch(switches::kDisableIOSPhysicalWeb)) {
     return false;
   }
 
   // Check if the finch experiment is turned on
   std::string group_name =
@@ skipping 50 matching lines @@
     return true;
 
   if (command_line->HasSwitch(switches::kDisableSuggestionsUI))
     return false;
 
   // By default, disable it.
   return false;
 }
 
 }  // namespace experimental_flags