[iOS] Add experimental new keyboard accessory view.

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 254 matching lines @@
   std::string group_name = base::FieldTrialList::FindFullName("IOSSigninPromo");
   return base::StartsWith(group_name, "Enabled",
                           base::CompareCase::INSENSITIVE_ASCII);
 }
 
 bool IsNativeAppLauncherEnabled() {
   return [[NSUserDefaults standardUserDefaults]
       boolForKey:@"NativeAppLauncherEnabled"];
 }
 
+bool IsNewKeyboardAccessoryViewEnabled() {
+  return [[NSUserDefaults standardUserDefaults]
+      boolForKey:@"NewKeyboardAccessoryViewEnabled"];
+}
+
 }  // namespace experimental_flags