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 8b7589ba8696053987166343f2a461f8a80ffaea..3b4dfe573bf6a5f38d4fee73b79175415c232947 100644
--- a/components/precache/core/precache_fetcher.cc
+++ b/components/precache/core/precache_fetcher.cc
@@ -280,6 +280,10 @@ void PrecacheFetcher::Fetcher::OnURLFetchDownloadProgress(
     response_bytes_ = network_response_bytes_ = current;
     was_cached_ = source->WasCached();
 
+    UMA_HISTOGRAM_CUSTOM_COUNTS("Precache.Fetch.ResponseBytes.NetworkWasted",
+                                network_response_bytes_, 1, kMaxResponseBytes,

[Steven Holte, 2016/08/30 22:33:26]

You probably shouldn't use kMaxResponseBytes here, since you shouldn't change
the bucket sizes later.  Suggest inlining the constant, or possibly using a
different value if you might adjust this one.

[Raj, 2016/09/14 00:14:36]

Done.

+                                100);
+
     // Cancel the download.
     network_url_fetcher_.reset();
     callback_.Run(*this);