Shift cookie system callbacks to OnceCallback to impedance match mojo.

ios/net/cookies/cookie_store_ios_test_util.h

 // Copyright 2017 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_NET_COOKIES_COOKIE_STORE_IOS_TEST_UTIL_H_
 #define IOS_NET_COOKIES_COOKIE_STORE_IOS_TEST_UTIL_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 20 matching lines @@
 
  private:
   // net::CookieMonster::PersistentCookieStore implementation:
   void Load(const LoadedCallback& loaded_callback) override;
   void LoadCookiesForKey(const std::string& key,
                          const LoadedCallback& loaded_callback) override;
   void AddCookie(const net::CanonicalCookie& cc) override;
   void UpdateCookieAccessTime(const net::CanonicalCookie& cc) override;
   void DeleteCookie(const net::CanonicalCookie& cc) override;
   void SetForceKeepSessionState() override;
-  void Flush(const base::Closure& callback) override;
+  void Flush(base::OnceClosure callback) override;
 
   ~TestPersistentCookieStore() override;
 
   const GURL kTestCookieURL;
   LoadedCallback loaded_callback_;
   bool flushed_;
 };
 
 // Helper callback to be passed to CookieStore::GetCookiesWithOptionsAsync().
 class GetCookieCallback {
@@ skipping 22 matching lines @@
 void SetCookie(const std::string& cookie_line,
                const GURL& url,
                net::CookieStore* store);
 
 // Clears the underlying NSHTTPCookieStorage.
 void ClearCookies();
 
 }  // namespace net
 
 #endif  // IOS_NET_COOKIES_COOKIE_STORE_IOS_TEST_UTIL_H_