Remove #pragma once from chrome/browser/extensions

chrome/browser/extensions/api/dns/mock_host_resolver_creator.h

 // Copyright (c) 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 CHROME_BROWSER_EXTENSIONS_API_DNS_MOCK_HOST_RESOLVER_CREATOR_H_
 #define CHROME_BROWSER_EXTENSIONS_API_DNS_MOCK_HOST_RESOLVER_CREATOR_H_
-#pragma once
 
 #include <string>
 
 #include "base/memory/ref_counted.h"
 #include "base/synchronization/waitable_event.h"
 
 namespace net {
 class MockHostResolver;
 }
 
@@ skipping 25 matching lines @@
   // it's created, which is actually a stronger rule than its real counterpart.
   // But that's fine; it's good practice.
   //
   // Plain pointer because we have to manage lifetime manually.
   net::MockHostResolver* mock_host_resolver_;
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_DNS_MOCK_HOST_RESOLVER_CREATOR_H_