[ios] Removed remaining code for URL spoofing interstitials.

ios/public/provider/chrome/browser/browser_constants.h

Index: ios/public/provider/chrome/browser/browser_constants.h
diff --git a/ios/public/provider/chrome/browser/browser_constants.h b/ios/public/provider/chrome/browser/browser_constants.h
deleted file mode 100644
index b40b26b18adedec1c3de48e59dce0ceca719f44e..0000000000000000000000000000000000000000
--- a/ios/public/provider/chrome/browser/browser_constants.h
+++ /dev/null
@@ -1,17 +0,0 @@
-// Copyright 2013 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.
-
-#ifndef IOS_PUBLIC_PROVIDER_CHROME_BROWSER_BROWSER_CONSTANTS_H_
-#define IOS_PUBLIC_PROVIDER_CHROME_BROWSER_BROWSER_CONSTANTS_H_
-
-namespace ios {
-
-// This string is a flag for net::SSLInfo signaling that the error is not a
-// typical certificate error, but rather is a spoofing attempt.
-// It can be used to customize the interstitial error page.
-extern const char kSpoofingAttemptFlag[];
-
-}  // namespace ios
-
-#endif  // IOS_PUBLIC_PROVIDER_CHROME_BROWSER_BROWSER_CONSTANTS_H_