Replace deprecated base::NonThreadSafe in content/child/fileapi in favor of SequenceChecker.

content/child/fileapi/webfilesystem_impl.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 CONTENT_CHILD_FILEAPI_WEBFILESYSTEM_IMPL_H_
 #define CONTENT_CHILD_FILEAPI_WEBFILESYSTEM_IMPL_H_
 
 #include <map>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
-#include "base/threading/non_thread_safe.h"
+#include "base/sequence_checker.h"
 #include "content/public/child/worker_thread.h"
 #include "third_party/WebKit/public/platform/WebFileSystem.h"
 
 namespace base {
 class SingleThreadTaskRunner;
 }
 
 namespace blink {
 class WebURL;
 class WebFileWriterClient;
 }
 
 namespace content {
 
 class WebFileSystemImpl : public blink::WebFileSystem,
-                          public WorkerThread::Observer,
-                          public base::NonThreadSafe {
+                          public WorkerThread::Observer {
  public:
   class WaitableCallbackResults;
 
   // Returns thread-specific instance.  If non-null |main_thread_loop|
   // is given and no thread-specific instance has been created it may
   // create a new instance.
   static WebFileSystemImpl* ThreadSpecificInstance(
       const scoped_refptr<base::SingleThreadTaskRunner>&
           main_thread_task_runner);
 
@@ skipping 59 matching lines @@
 
   WaitableCallbackResults* MaybeCreateWaitableResults(
       const blink::WebFileSystemCallbacks& callbacks, int callbacks_id);
 
   scoped_refptr<base::SingleThreadTaskRunner> main_thread_task_runner_;
 
   CallbacksMap callbacks_;
   int next_callbacks_id_;
   WaitableCallbackResultsMap waitable_results_;
 
+  SEQUENCE_CHECKER(sequence_checker_);
+
   DISALLOW_COPY_AND_ASSIGN(WebFileSystemImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_CHILD_FILEAPI_WEBFILESYSTEM_IMPL_H_