net: Update FileStream to use base::File instead of PlatformFile.

base/files/file.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 BASE_FILES_FILE_H_
 #define BASE_FILES_FILE_H_
 
 #include "build/build_config.h"
 #if defined(OS_WIN)
 #include <windows.h>
@@ skipping 246 matching lines @@
   // POSIX-specific semantics:
   //  * Locks are advisory only.
   //  * Within a process, locking the same file (by the same or new handle)
   //    will succeed.
   //  * Closing any descriptor on a given file releases the lock.
   Error Lock();
 
   // Unlock a file previously locked.
   Error Unlock();
 
+  bool async() const { return async_; }
+
 #if defined(OS_WIN)
   static Error OSErrorToFileError(DWORD last_error);
 #elif defined(OS_POSIX)
   static Error OSErrorToFileError(int saved_errno);
 #endif
 
  private:
   void SetPlatformFile(PlatformFile file);
 
 #if defined(OS_WIN)
   win::ScopedHandle file_;
 #elif defined(OS_POSIX)
   PlatformFile file_;
 #endif
 
   Error error_details_;
   bool created_;
   bool async_;
 };
 
 }  // namespace base
 
 #endif  // BASE_FILES_FILE_H_