Update PPAPI IDL generator to define versioned structs, and unversioned typedef.

ppapi/thunk/ppb_file_system_thunk.cc

Index: ppapi/thunk/ppb_file_system_thunk.cc
diff --git a/ppapi/thunk/ppb_file_system_thunk.cc b/ppapi/thunk/ppb_file_system_thunk.cc
index ad2c8db16e962e9a02fde72a638d91269b21be33..59612399b5d3202969e72a56e33646f5c560b601 100644
--- a/ppapi/thunk/ppb_file_system_thunk.cc
+++ b/ppapi/thunk/ppb_file_system_thunk.cc
@@ -54,7 +54,7 @@ const PPB_FileSystem g_ppb_file_system_thunk = {
 
 }  // namespace
 
-const PPB_FileSystem* GetPPB_FileSystem_Thunk() {
+const PPB_FileSystem_1_0* GetPPB_FileSystem_1_0_Thunk() {
   return &g_ppb_file_system_thunk;
 }