Report the wasted network bytes when resource prefetches hit max limit

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index aca0658928cccb66e0936859f248eb27d7c10426..05272d18564eb42b0070edd316cfc666d96560d2 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -44732,6 +44732,17 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Precache.Fetch.ResponseBytes.NetworkWasted" units="bytes">
+  <owner>rajendrant@chromium.org</owner>
+  <owner>bengr@chromium.org</owner>
+  <summary>
+    The total number of response bytes received over the network for a wasted
+    resource precache fetch. Logged when a partially downloaded resource
+    precache fetch gets cancelled due to per-resource size limit or max precache
+    size limit.
+  </summary>
+</histogram>
+
 <histogram name="Precache.Fetch.ResponseBytes.Total" units="bytes">
   <owner>twifkak@chromium.org</owner>
   <owner>bengr@chromium.org</owner>