Remove some PlatformFile instances from ChromeOS Drive.

chrome/browser/chromeos/drive/local_file_reader.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_CHROMEOS_DRIVE_LOCAL_FILE_READER_H_
 #define CHROME_BROWSER_CHROMEOS_DRIVE_LOCAL_FILE_READER_H_
 
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
-#include "base/platform_file.h"
 #include "net/base/completion_callback.h"
+#include "net/base/file_stream.h"
 
 namespace base {
 class FilePath;
 class SequencedTaskRunner;
 }  // namespace base
 
 namespace net {
 class IOBuffer;
-}  // namespace
+}  // namespace net
 
 namespace drive {
 namespace util {
 
 // This is simple local file reader implementation focusing on Drive's use
 // case. All the operations run on |sequenced_task_runner| asynchronously and
 // the result will be notified to the caller via |callback|s on the caller's
 // thread.
 class LocalFileReader {
  public:
@@ skipping 10 matching lines @@
 
   // Reads the file and copies the data into |buffer|. |buffer_length|
   // is the length of |buffer|.
   // Upon completion, |callback| will be called with the result.
   // |callback| must not be null.
   void Read(net::IOBuffer* buffer,
             int buffer_length,
             const net::CompletionCallback& callback);
 
  private:
-  // The thin wrapper for the platform file to handle closing correctly.
-  class ScopedPlatformFile;
+  void DidOpen(const net::CompletionCallback& callback,
+               int64 offset,
+               int error);
+  void DidSeek(const net::CompletionCallback& callback,
+               int64 offset,
+               int64 error);
 
-  // Part of Open(). Called after the open() operation task running
-  // on blocking pool.
-  void OpenAfterBlockingPoolTask(
-      const net::CompletionCallback& callback,
-      ScopedPlatformFile* result_platform_file,
-      int open_result);
-
-  scoped_refptr<base::SequencedTaskRunner> sequenced_task_runner_;
-  base::PlatformFile platform_file_;
+  net::FileStream file_stream_;
 
   // Note: This should remain the last member so it'll be destroyed and
   // invalidate the weak pointers before any other members are destroyed.
   base::WeakPtrFactory<LocalFileReader> weak_ptr_factory_;
   DISALLOW_COPY_AND_ASSIGN(LocalFileReader);
 };
 
 }  // namespace util
 }  // namespace drive
 
 #endif  // CHROME_BROWSER_CHROMEOS_DRIVE_LOCAL_FILE_READER_H_