Cleanup: Remove unneeded browser_thread.h includes.

chrome/browser/extensions/api/system_info/system_info_provider.h

 // 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 CHROME_BROWSER_EXTENSIONS_API_SYSTEM_INFO_SYSTEM_INFO_PROVIDER_H_
 #define CHROME_BROWSER_EXTENSIONS_API_SYSTEM_INFO_SYSTEM_INFO_PROVIDER_H_
 
 #include <queue>
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "base/threading/sequenced_worker_pool.h"
-#include "content/public/browser/browser_thread.h"
 
 namespace extensions {
 
 // An abstract base class for all kinds of system information providers. Each
 // kind of SystemInfoProvider is a single shared instance. It is created if
 // needed, and destroyed at exit time. This is done via LazyInstance and
 // scoped_refptr.
 //
 // The SystemInfoProvider is designed to query system information on the worker
 // pool. It also maintains a queue of callbacks on the UI thread which are
@@ skipping 65 matching lines @@
   // Sequenced worker pool to make the operation of querying information get
   // executed in order.
   scoped_refptr<base::SequencedTaskRunner> worker_pool_;
 
   DISALLOW_COPY_AND_ASSIGN(SystemInfoProvider);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_SYSTEM_INFO_SYSTEM_INFO_PROVIDER_H_