Disable inclusion of x509_certificate_model.h on unsupported platforms.

chrome/common/net/x509_certificate_model.h

Index: chrome/common/net/x509_certificate_model.h
diff --git a/chrome/common/net/x509_certificate_model.h b/chrome/common/net/x509_certificate_model.h
index 6a8987a52f15eeba8cba3cb2d64829bc9d2c6fd0..b6062399c19ab8645ac9bae7b29b8aa1878159d6 100644
--- a/chrome/common/net/x509_certificate_model.h
+++ b/chrome/common/net/x509_certificate_model.h
@@ -5,6 +5,10 @@
 #ifndef CHROME_COMMON_NET_X509_CERTIFICATE_MODEL_H_
 #define CHROME_COMMON_NET_X509_CERTIFICATE_MODEL_H_
 
+#if !defined(USE_NSS_CERTS) && !defined(USE_OPENSSL_CERTS)
+#error "This file must be built with either USE_NSS_CERTS or USE_OPENSSL_CERTS."
+#else
+
 #include <stddef.h>
 
 #include "net/cert/cert_type.h"
@@ -124,4 +128,6 @@ std::string ProcessRawBits(const unsigned char* data,
 
 }  // namespace x509_certificate_model
 
+#endif  // !defined(USE_NSS_CERTS) && !defined(USE_OPENSSL_CERTS)
+
 #endif  // CHROME_COMMON_NET_X509_CERTIFICATE_MODEL_H_