Add HTTP2_CODE_COUNT_N API and decompress_failure_3 counters to debug source of
DECOMPRESS_FAILURE errors.

Note that on any code path multiple of these macros are expected to be hit.

gfe-relnote: n/a, add CODE_COUNT macros for debugging.
PiperOrigin-RevId: 292355227
Change-Id: I9b02119c30af03016073307feedee896f397b24c
diff --git a/http2/platform/api/http2_flags.h b/http2/platform/api/http2_flags.h
index 08f95da..097d35e 100644
--- a/http2/platform/api/http2_flags.h
+++ b/http2/platform/api/http2_flags.h
@@ -11,4 +11,6 @@
 #define SetHttp2ReloadableFlag(flag, value) \
   SetHttp2ReloadableFlagImpl(flag, value)
 
+#define HTTP2_CODE_COUNT_N HTTP2_CODE_COUNT_N_IMPL
+
 #endif  // QUICHE_HTTP2_PLATFORM_API_HTTP2_FLAGS_H_