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

ppapi/thunk/ppb_widget_thunk.cc

Index: ppapi/thunk/ppb_widget_thunk.cc
diff --git a/ppapi/thunk/ppb_widget_thunk.cc b/ppapi/thunk/ppb_widget_thunk.cc
index ec77352e40f5b53bbeaa474235fd16650d7a1804..333f54f65b217690fd116fa0084e7f3fa31e5f8c 100644
--- a/ppapi/thunk/ppb_widget_thunk.cc
+++ b/ppapi/thunk/ppb_widget_thunk.cc
@@ -54,7 +54,7 @@ const PPB_Widget_Dev g_ppb_widget_thunk = {
 
 }  // namespace
 
-const PPB_Widget_Dev* GetPPB_Widget_Dev_Thunk() {
+const PPB_Widget_Dev_0_3* GetPPB_Widget_Dev_0_3_Thunk() {
   return &g_ppb_widget_thunk;
 }