MTPFileStreamReader::Read should return 0 instead of error on read-from-eof.

chrome/browser/media_galleries/linux/mtp_device_task_helper.cc

 // 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.
 
 #include "chrome/browser/media_galleries/linux/mtp_device_task_helper.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "base/numerics/safe_conversions.h"
@@ skipping 196 matching lines @@
   if (error) {
     return HandleDeviceError(request.error_callback,
                              base::File::FILE_ERROR_FAILED);
   }
 
   base::File::Info file_info = FileInfoFromMTPFileEntry(file_entry);
   if (file_info.is_directory) {
     return HandleDeviceError(request.error_callback,
                              base::File::FILE_ERROR_NOT_A_FILE);
   } else if (file_info.size < 0 || file_info.size > kuint32max ||
-             request.offset >= file_info.size) {
+             request.offset > file_info.size) {
     return HandleDeviceError(request.error_callback,
                              base::File::FILE_ERROR_FAILED);
+  } else if (request.offset == file_info.size) {
+    content::BrowserThread::PostTask(content::BrowserThread::IO,
+                                     FROM_HERE,
+                                     base::Bind(request.success_callback,
+                                                file_info, 0u));
+    return;
   }
 
   uint32 bytes_to_read = std::min(
       base::checked_cast<uint32>(request.buf_len),
       base::saturated_cast<uint32>(file_info.size - request.offset));
 
   GetMediaTransferProtocolManager()->ReadFileChunkByPath(
       device_handle_,
       request.device_file_relative_path,
       base::checked_cast<uint32>(request.offset),
@@ skipping 23 matching lines @@
 }
 
 void MTPDeviceTaskHelper::HandleDeviceError(
     const ErrorCallback& error_callback,
     base::File::Error error) const {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   content::BrowserThread::PostTask(content::BrowserThread::IO,
                                    FROM_HERE,
                                    base::Bind(error_callback, error));
 }