Detect file system errors during downloads.

content/browser/download/download_file_unittest.cc

 // Copyright (c) 2011 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 "base/file_util.h"
 #include "base/message_loop.h"
 #include "base/scoped_temp_dir.h"
 #include "base/string_number_conversions.h"
 #include "chrome/browser/download/download_util.h"
 #include "chrome/browser/download/mock_download_manager_delegate.h"
@@ skipping 61 matching lines @@
     EXPECT_FALSE((*file)->in_progress());
     EXPECT_EQ(static_cast<int64>(expected_data_.size()),
               (*file)->bytes_so_far());
 
     // Make sure the data has been properly written to disk.
     std::string disk_data;
     EXPECT_TRUE(file_util::ReadFileToString((*file)->full_path(),
                                             &disk_data));
     EXPECT_EQ(expected_data_, disk_data);
 
-    // Make sure the mock BrowserThread outlives the DownloadFile to satisfy
-    // thread checks inside it.
+    // Make sure the Browser and File threads outlive the DownloadFile
+    // to satisfy thread checks inside it.
     file->reset();
   }
 
   void AppendDataToFile(scoped_ptr<DownloadFile>* file,
                         const std::string& data) {
     EXPECT_TRUE((*file)->in_progress());
     (*file)->AppendDataToFile(data.data(), data.size());
     expected_data_ += data;
     EXPECT_EQ(static_cast<int64>(expected_data_.size()),
               (*file)->bytes_so_far());
@@ skipping 93 matching lines @@
   // Check the files.
   EXPECT_FALSE(file_util::PathExists(path_3));
   EXPECT_TRUE(file_util::PathExists(path_4));
 
   // Check the hash.
   EXPECT_TRUE(download_file_->GetSha256Hash(&hash));
   EXPECT_EQ(kDataHash, base::HexEncode(hash.data(), hash.size()));
 
   DestroyDownloadFile(&download_file_, 0);
 }