Make USE_OPENSSL and USE_NSS mutually exclusive

chrome/browser/importer/nss_decryptor.h

Index: chrome/browser/importer/nss_decryptor.h
diff --git a/chrome/browser/importer/nss_decryptor.h b/chrome/browser/importer/nss_decryptor.h
index 8361d17a6a4f2f3e86a3a63967c4c4f42f2480d6..9896a14e1a595001d00619a20850e35e70b9e188 100644
--- a/chrome/browser/importer/nss_decryptor.h
+++ b/chrome/browser/importer/nss_decryptor.h
@@ -12,6 +12,13 @@
 #include "chrome/browser/importer/nss_decryptor_mac.h"
 #elif defined(OS_WIN)
 #include "chrome/browser/importer/nss_decryptor_win.h"
+#elif defined(USE_OPENSSL)
+// TODO(joth): It should be an error to include this file with USE_OPENSSL
+// defined. (Unless there is a way to do nss decrypt with OpenSSL). Ideally
+// we remove the importers that depend on NSS when doing USE_OPENSSL builds, but
+// that is going to take some non-trivial refactoring so in the meantime we're
+// just falling back to a no-op implementation.
+#include "chrome/browser/importer/nss_decryptor_null.h"
 #elif defined(USE_NSS)
 #include "chrome/browser/importer/nss_decryptor_system_nss.h"
 #endif