Add a whitelist check for nacl-nonsfi mode

extensions/common/manifest_handlers/shared_module_info.cc

Index: extensions/common/manifest_handlers/shared_module_info.cc
diff --git a/extensions/common/manifest_handlers/shared_module_info.cc b/extensions/common/manifest_handlers/shared_module_info.cc
index ac95ee5b07440270e2afb9bb64272c2981473597..66a06e9a6a74af0cab303f075a12a435b180373d 100644
--- a/extensions/common/manifest_handlers/shared_module_info.cc
+++ b/extensions/common/manifest_handlers/shared_module_info.cc
@@ -86,6 +86,11 @@ bool SharedModuleInfo::IsExportAllowed(const Extension* extension,
 // static
 bool SharedModuleInfo::IsExportAllowedByWhitelist(const Extension* extension,
                                                   const std::string& other_id) {
+  // Sanity check. In case the caller did not check |extension| to make sure it
+  // is a shared module, we do not want it to appear that the extension with
+  // |other_id| importing |extension| is valid.
+  if (!SharedModuleInfo::IsSharedModule(extension))
+    return false;
   const SharedModuleInfo& info = GetSharedModuleInfo(extension);
   if (info.export_whitelist_.empty())
     return true;