Refactor AppendToFile and WriteFileDescriptor

chrome/browser/net/net_log_temp_file_unittest.cc

 // Copyright (c) 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/net/net_log_temp_file.h"
 
 #include "base/basictypes.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/message_loop/message_loop.h"
@@ skipping 279 matching lines @@
 
   net_log_temp_file_->ProcessCommand(NetLogTempFile::DO_STOP);
   VerifyFileAndStateAfterDoStop();
 
   int64 stop_file_size;
   EXPECT_TRUE(base::GetFileSize(net_export_log_, &stop_file_size));
   EXPECT_GE(stop_file_size, start_file_size);
 
   // Add some junk at the end of the file.
   std::string junk_data("Hello");
-  EXPECT_GT(base::AppendToFile(
-      net_export_log_, junk_data.c_str(), junk_data.size()), 0);
+  EXPECT_TRUE(base::AppendToFile(net_export_log_, junk_data.c_str(),
+                                 junk_data.size()));
 
   int64 junk_file_size;
   EXPECT_TRUE(base::GetFileSize(net_export_log_, &junk_file_size));
   EXPECT_GT(junk_file_size, stop_file_size);
 
   // Execute DO_START/DO_STOP commands and make sure the file is back to the
   // size before addition of junk data.
   net_log_temp_file_->ProcessCommand(NetLogTempFile::DO_START);
   VerifyFileAndStateAfterDoStart();
 
@@ skipping 30 matching lines @@
   // Log an event.
   net_log_->AddGlobalEntry(net::NetLog::TYPE_CANCELLED);
 
   net_log_temp_file_->ProcessCommand(NetLogTempFile::DO_STOP);
   VerifyFileAndStateAfterDoStop();
 
   int64 new_stop_file_size;
   EXPECT_TRUE(base::GetFileSize(net_export_log_, &new_stop_file_size));
   EXPECT_GE(new_stop_file_size, stop_file_size);
 }