[Pepper] Wire up append mode writing support of FileIO

ppapi/shared_impl/file_growth.cc

 // Copyright 2014 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 "ppapi/shared_impl/file_growth.h"
 
 #include "base/logging.h"
 
 namespace ppapi {
 
 FileGrowth::FileGrowth()
     : max_written_offset(0),
       append_mode_write_amount(0) {
 }
 
 FileGrowth::FileGrowth(int64_t max_written_offset,
                        int64_t append_mode_write_amount)
     : max_written_offset(max_written_offset),
       append_mode_write_amount(append_mode_write_amount) {
   DCHECK_LE(0, max_written_offset);
   DCHECK_LE(0, append_mode_write_amount);
 }
 
+FileGrowthMap FileSizeMapToFileGrowthMap(const FileSizeMap& file_sizes) {
+  FileGrowthMap file_growths;
+  for (FileSizeMap::const_iterator it = file_sizes.begin();
+       it != file_sizes.end(); ++it)
+    file_growths[it->first] = FileGrowth(it->second, 0);
+  return file_growths;
+}
+
+FileSizeMap FileGrowthMapToFileSizeMap(const FileGrowthMap& file_growths) {
+  FileSizeMap file_sizes;
+  for (FileGrowthMap::const_iterator it = file_growths.begin();
+       it != file_growths.end(); ++it)
+    file_sizes[it->first] = it->second.max_written_offset;
+  return file_sizes;
+}
+
 }  // namespace ppapi