[PageLoadMetrics] Record bytes usage per page

chrome/browser/page_load_metrics/page_load_metrics_observer.h

Index: chrome/browser/page_load_metrics/page_load_metrics_observer.h
diff --git a/chrome/browser/page_load_metrics/page_load_metrics_observer.h b/chrome/browser/page_load_metrics/page_load_metrics_observer.h
index 7d4c1af22284e8a4bf76a4eceb04160ef110cacc..3de3df0b45ac9dc9074f9b0aea1cee1c28c7001e 100644
--- a/chrome/browser/page_load_metrics/page_load_metrics_observer.h
+++ b/chrome/browser/page_load_metrics/page_load_metrics_observer.h
@@ -118,6 +118,8 @@ struct PageLoadExtraInfo {
       const base::Optional<base::TimeDelta>& time_to_abort,
       int num_cache_requests,
       int num_network_requests,
+      int64_t cache_bytes,
+      int64_t net_bytes,
       const PageLoadMetadata& metadata);
 
   PageLoadExtraInfo(const PageLoadExtraInfo& other);
@@ -168,6 +170,10 @@ struct PageLoadExtraInfo {
   int num_cache_requests;
   int num_network_requests;
 
+  // Bytes consumed by this page.
+  int64_t cache_bytes;
+  int64_t network_bytes;

[Bryan McQuade, 2016/12/16 14:28:45]

i think it's implicit, but just to be extra clear, can you add a comment to
explain that this is HTTP bytes on the wire, excluding HTTP headers? e.g. it's
the gzipped size of a response, rather than the post-ungzip size?

Is the same true for cache bytes? Both network and cache bytes are "wire sizes",
less HTTP headers?

[jkarlin, 2016/12/19 19:26:01]

Done.

+
   // Extra information supplied to the page load metrics system from the
   // renderer.
   const PageLoadMetadata metadata;