Enable warning 4389 as an error on windows builds. This will make...

base/file_util_win.cc

 // Copyright (c) 2010 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 <windows.h>
 #include <propvarutil.h>
 #include <shellapi.h>
 #include <shlobj.h>
@@ skipping 638 matching lines @@
   ScopedHandle file(CreateFile(filename.value().c_str(),
                                GENERIC_READ,
                                FILE_SHARE_READ | FILE_SHARE_WRITE,
                                NULL,
                                OPEN_EXISTING,
                                FILE_FLAG_SEQUENTIAL_SCAN,
                                NULL));
   if (file == INVALID_HANDLE_VALUE)
     return -1;
 
-  int ret_value;
   DWORD read;
-  if (::ReadFile(file, data, size, &read, NULL) && read == size) {
-    ret_value = static_cast<int>(read);
-  } else {
-    ret_value = -1;
-  }
-
-  return ret_value;
+  if (::ReadFile(file, data, size, &read, NULL) &&
+      static_cast<int>(read) == size)
+    return read;
+  return -1;
 }
 
 int WriteFile(const FilePath& filename, const char* data, int size) {
   ScopedHandle file(CreateFile(filename.value().c_str(),
                                GENERIC_WRITE,
                                0,
                                NULL,
                                CREATE_ALWAYS,
                                0,
                                NULL));
   if (file == INVALID_HANDLE_VALUE) {
     LOG(WARNING) << "CreateFile failed for path " << filename.value() <<
         " error code=" << GetLastError() <<
         " error text=" << win_util::FormatLastWin32Error();
     return -1;
   }
 
   DWORD written;
   BOOL result = ::WriteFile(file, data, size, &written, NULL);
-  if (result && written == size)
-    return static_cast<int>(written);
+  if (result && static_cast<int>(written) == size)
+    return written;
 
   if (!result) {
     // WriteFile failed.
     LOG(WARNING) << "writing file " << filename.value() <<
         " failed, error code=" << GetLastError() <<
         " description=" << win_util::FormatLastWin32Error();
   } else {
     // Didn't write all the bytes.
     LOG(WARNING) << "wrote" << written << " bytes to " <<
         filename.value() << " expected " << size;
@@ skipping 200 matching lines @@
 }
 
 bool HasFileBeenModifiedSince(const FileEnumerator::FindInfo& find_info,
                               const base::Time& cutoff_time) {
   long result = CompareFileTime(&find_info.ftLastWriteTime,
                                 &cutoff_time.ToFileTime());
   return result == 1 || result == 0;
 }
 
 }  // namespace file_util