Refactor AppendToFile and WriteFileDescriptor

ui/base/resource/data_pack_unittest.cc

 // 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.
 
 #include "base/files/file.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/files/scoped_temp_dir.h"
 #include "base/path_service.h"
 #include "base/strings/string_piece.h"
@@ skipping 84 matching lines @@
 TEST(DataPackTest, LoadFromFileRegion) {
   base::ScopedTempDir dir;
   ASSERT_TRUE(dir.CreateUniqueTempDir());
   base::FilePath data_path = dir.path().Append(FILE_PATH_LITERAL("sample.pak"));
 
   // Construct a file which has a non page-aligned zero-filled header followed
   // by the actual pak file content.
   const char kPadding[5678] = {0};
   ASSERT_EQ(static_cast<int>(sizeof(kPadding)),
             base::WriteFile(data_path, kPadding, sizeof(kPadding)));
-  ASSERT_EQ(static_cast<int>(kSamplePakSize),
-            base::AppendToFile(data_path, kSamplePakContents, kSamplePakSize));
+  ASSERT_TRUE(base::AppendToFile(
+      data_path, kSamplePakContents, kSamplePakSize));
 
   base::File file(data_path, base::File::FLAG_OPEN | base::File::FLAG_READ);
   ASSERT_TRUE(file.IsValid());
 
   // Load the file through the data pack API.
   DataPack pack(SCALE_FACTOR_100P);
   base::MemoryMappedFile::Region region(sizeof(kPadding), kSamplePakSize);
   ASSERT_TRUE(pack.LoadFromFileRegion(file.Pass(), region));
 
   base::StringPiece data;
@@ skipping 93 matching lines @@
                             kSampleCorruptPakSize),
             static_cast<int>(kSampleCorruptPakSize));
 
   // Reading asset #10 should now fail as it extends past the end of the file.
   ASSERT_TRUE(pack.HasResource(10));
   ASSERT_FALSE(pack.GetStringPiece(10, &data));
 }
 #endif
 
 }  // namespace ui