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

ppapi/tests/test_buffer.h

Index: ppapi/tests/test_buffer.h
diff --git a/ppapi/tests/test_buffer.h b/ppapi/tests/test_buffer.h
index 7dea01769b2cb1b848453dab3608392decbfc47f..1e80ba014cf17d40529d93091157ef0270df2d83 100644
--- a/ppapi/tests/test_buffer.h
+++ b/ppapi/tests/test_buffer.h
@@ -7,10 +7,9 @@
 
 #include <string>
 
+#include "ppapi/c/dev/ppb_buffer_dev.h"
 #include "ppapi/tests/test_case.h"
 
-struct PPB_Buffer_Dev;
-
 class TestBuffer : public TestCase {
  public:
   explicit TestBuffer(TestingInstance* instance) : TestCase(instance) {}