[NoStatePrefetch] Do not send responses to renderer in prefetch mode.

content/common/resource_request.h

Index: content/common/resource_request.h
diff --git a/content/common/resource_request.h b/content/common/resource_request.h
index 83263cc5c1ccd40cdbae11011e65143a32e1fd3d..337e07529ceb5c345cbb6a4b796df7122391778b 100644
--- a/content/common/resource_request.h
+++ b/content/common/resource_request.h
@@ -173,6 +173,10 @@ struct CONTENT_EXPORT ResourceRequest {
 
   // Wether or not the initiator of this request is a secure context.
   bool initiated_in_secure_context = false;
+
+  // Wether the request is in "prefetch-only" mode and is not intended to be
+  // rendered.
+  bool is_prefetch_only = false;
 };
 
 }  // namespace content