Keep track of how many documents had a resource intercepted by foreign fetch.

content/public/common/resource_response_info.h

Index: content/public/common/resource_response_info.h
diff --git a/content/public/common/resource_response_info.h b/content/public/common/resource_response_info.h
index a117de8ca637688493fe4b58960078c0d1f75a72..b0008adadc88fb1b2403171f0c15a776d722c179 100644
--- a/content/public/common/resource_response_info.h
+++ b/content/public/common/resource_response_info.h
@@ -118,6 +118,9 @@ struct CONTENT_EXPORT ResourceResponseInfo {
   // True if the response was fetched by a ServiceWorker.
   bool was_fetched_via_service_worker;
 
+  // True if the response was fetched by a foreign fetch ServiceWorker;
+  bool was_fetched_via_foreign_fetch;
+
   // True when the request whoes mode is |CORS| or |CORS-with-forced-preflight|
   // is sent to a ServiceWorker but FetchEvent.respondWith is not called. So the
   // renderer have to resend the request with skip service worker flag