[PageLoadMetrics] Record bytes usage per page

chrome/browser/page_load_metrics/page_load_tracker.h

Index: chrome/browser/page_load_metrics/page_load_tracker.h
diff --git a/chrome/browser/page_load_metrics/page_load_tracker.h b/chrome/browser/page_load_metrics/page_load_tracker.h
index 817bc4fd8be650b35b8af88e66011a881d9faae7..b58a86385d38453e4a239836ee9a60a985f2238f 100644
--- a/chrome/browser/page_load_metrics/page_load_tracker.h
+++ b/chrome/browser/page_load_metrics/page_load_tracker.h
@@ -152,7 +152,7 @@ class PageLoadTracker {
   bool UpdateTiming(const PageLoadTiming& timing,
                     const PageLoadMetadata& metadata);
 
-  void OnLoadedSubresource(bool was_cached);
+  void OnLoadedResource(bool was_cached, int64_t raw_body_bytes);
 
   // Signals that we should stop tracking metrics for the associated page load.
   // We may stop tracking a page load if it doesn't meet the criteria for
@@ -285,6 +285,11 @@ class PageLoadTracker {
   int num_cache_requests_;
   int num_network_requests_;
 
+  // The number of body (not header) prefilter bytes consumed by requests for
+  // the page.
+  int64_t cache_bytes_;
+  int64_t network_bytes_;
+
   // Whether this page load was user initiated.
   UserInitiatedInfo user_initiated_info_;