[Not for review] record detailed time breakdown of SW related requests.

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 278566ce853daafd36349c1fbf9f03cafc65c514..ec129ca05b564560fc792b2c9ac363cb391116d5 100644
--- a/content/common/resource_request.h
+++ b/content/common/resource_request.h
@@ -10,6 +10,7 @@
 
 #include "base/memory/ref_counted.h"
 #include "base/optional.h"
+#include "base/time/time.h"
 #include "content/common/content_export.h"
 #include "content/common/navigation_params.h"
 #include "content/common/resource_request_body_impl.h"
@@ -40,6 +41,9 @@ struct CONTENT_EXPORT ResourceRequest {
   // The absolute requested URL encoded in ASCII per the rules of RFC-2396.
   GURL url;
 
+  // TimeTicks::Now() when the renderer sent the request to the browser.
+  base::TimeTicks request_start;
+
   // URL representing the first-party origin for the request, which may be
   // checked by the third-party cookie blocking policy. This is usually the URL
   // of the document in the top-level window. Leaving it empty may lead to