Add compile assertions to enforce the sizes of all structs and enums in the C...

ppapi/c/pp_instance.h

Index: ppapi/c/pp_instance.h
===================================================================
--- ppapi/c/pp_instance.h	(revision 68603)
+++ ppapi/c/pp_instance.h	(working copy)
@@ -13,6 +13,7 @@
  * @{
  */
 
+#include "ppapi/c/pp_macros.h"
 #include "ppapi/c/pp_stdint.h"
 
 /** A PP_Instance uniquely identifies one plugin instance, which is one time
@@ -24,6 +25,7 @@
  * indicate a "NULL handle."
  */
 typedef int64_t PP_Instance;
+PP_COMPILE_ASSERT_SIZE_IN_BYTES(PP_Instance, 8);
 
 /**
  * @}