[Pepper] Wire up append mode writing support of FileIO

ppapi/shared_impl/file_growth.cc

Index: ppapi/shared_impl/file_growth.cc
diff --git a/ppapi/shared_impl/file_growth.cc b/ppapi/shared_impl/file_growth.cc
index 002bd0fb1c3b1e9c8468af508483c3960fd815c2..5fc7bcce27bd3949ff01b853727b97721b9323aa 100644
--- a/ppapi/shared_impl/file_growth.cc
+++ b/ppapi/shared_impl/file_growth.cc
@@ -21,4 +21,20 @@ FileGrowth::FileGrowth(int64_t 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