Report the wasted network bytes when resource prefetches hit max limit

components/precache/core/precache_fetcher.cc

Index: components/precache/core/precache_fetcher.cc
diff --git a/components/precache/core/precache_fetcher.cc b/components/precache/core/precache_fetcher.cc
index a5cf65086d2f665ced1263529f2e433788d25c9e..51a0325701a7dd04ed3aa6d39bdee99b5a9cc6db 100644
--- a/components/precache/core/precache_fetcher.cc
+++ b/components/precache/core/precache_fetcher.cc
@@ -243,10 +243,14 @@ void PrecacheFetcher::Fetcher::OnURLFetchDownloadProgress(
     // Cancel the download.
     network_url_fetcher_.reset();
 
-    // Call the completion callback, to attempt the next download, or to trigger
-    // cleanup in precache_delegate_->OnDone().
     response_bytes_ = network_response_bytes_ = current;
 
+    UMA_HISTOGRAM_CUSTOM_COUNTS("Precache.Fetch.ResponseBytes.NetworkWasted",
+                                network_response_bytes_, 1, kMaxResponseBytes,
+                                100);
+
+    // Call the completion callback, to attempt the next download, or to trigger
+    // cleanup in precache_delegate_->OnDone().
     callback_.Run(*this);
   }
 }