Convert base::MemoryMappedFile to use File instead of PlatformFile.

media/base/media_file_checker.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 MEDIA_BASE_MEDIA_FILE_CHECKER_H_
 #define MEDIA_BASE_MEDIA_FILE_CHECKER_H_
 
 #include "base/basictypes.h"
-#include "base/files/scoped_platform_file_closer.h"
-#include "base/platform_file.h"
+#include "base/files/file.h"
 #include "media/base/media_export.h"
 
 namespace base {
 class TimeDelta;
 }
 
 namespace media {
 
 // This class tries to determine if a file is a valid media file. The entire
 // file is not decoded so a positive result from this class does not make the
 // file safe to use in the browser process.
 class MEDIA_EXPORT MediaFileChecker {
  public:
-  explicit MediaFileChecker(const base::PlatformFile& file);
+  explicit MediaFileChecker(base::File file);
   ~MediaFileChecker();
 
   // After opening |file|, up to |check_time| amount of wall-clock time is spent
   // decoding the file. The amount of audio/video data decoded will depend on
   // the bitrate of the file and the speed of the CPU.
   bool Start(base::TimeDelta check_time);
 
  private:
-  base::PlatformFile file_;
-  base::ScopedPlatformFileCloser file_closer_;
+  base::File file_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaFileChecker);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_MEDIA_FILE_CHECKER_H_