[Pepper] Wire up append mode writing support of FileIO

ppapi/shared_impl/file_growth.h

Index: ppapi/shared_impl/file_growth.h
diff --git a/ppapi/shared_impl/file_growth.h b/ppapi/shared_impl/file_growth.h
index b9e83ec3b1de9b65c74b4b3100ea3522ee029dba..23f12e0298c69f2ad8cec23990f0b3cc3f1413f3 100644
--- a/ppapi/shared_impl/file_growth.h
+++ b/ppapi/shared_impl/file_growth.h
@@ -23,6 +23,11 @@ struct PPAPI_SHARED_EXPORT FileGrowth {
 typedef std::map<int32_t, FileGrowth> FileGrowthMap;
 typedef std::map<int32_t, int64_t> FileSizeMap;
 
+PPAPI_SHARED_EXPORT FileGrowthMap FileSizeMapToFileGrowthMapForTesting(
+    const FileSizeMap& file_sizes);
+PPAPI_SHARED_EXPORT FileSizeMap FileGrowthMapToFileSizeMapForTesting(
+    const FileGrowthMap& file_growths);
+
 }  // namespace ppapi
 
 #endif  // PPAPI_SHARED_IMPL_FILE_GROWTH_H_