ios: Cleanup class/struct forward declarations

ios/chrome/browser/net/cookie_util.h

 // 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.
 
 #ifndef IOS_CHROME_BROWSER_NET_COOKIE_UTIL_H_
 #define IOS_CHROME_BROWSER_NET_COOKIE_UTIL_H_
 
 #include <memory>
 
 #include "base/files/file_path.h"
 #include "base/memory/ref_counted.h"
 #include "net/cookies/canonical_cookie.h"
 
-namespace base {
-class SequencedTaskRunner;
-}
-
 namespace ios {
 class ChromeBrowserState;
 }
 
 namespace net {
 class CookieCryptoDelegate;
 class CookieStore;
 }
 
 namespace cookie_util {
@@ skipping 55 matching lines @@
 // Current implementation returns true if the device has rebooted since the
 // last time cookies have been cleared.
 bool ShouldClearSessionCookies();
 
 // Clears the session cookies for |browser_state|.
 void ClearSessionCookies(ios::ChromeBrowserState* browser_state);
 
 }  // namespace cookie_util
 
 #endif  // IOS_CHROME_BROWSER_NET_COOKIE_UTIL_H_