Log predictor database size on startup

chrome/browser/net/predictor.cc

Index: chrome/browser/net/predictor.cc
diff --git a/chrome/browser/net/predictor.cc b/chrome/browser/net/predictor.cc
index e375df45c21697a1cf163a67ddbea5c0ee2f9b55..10149461984c421a040995e2721cf0241fd94754 100644
--- a/chrome/browser/net/predictor.cc
+++ b/chrome/browser/net/predictor.cc
@@ -672,6 +672,8 @@ void Predictor::FinalizeInitializationOnIOThread(
   DnsPrefetchMotivatedList(startup_urls, UrlInfo::STARTUP_LIST_MOTIVATED);
 
   DeserializeReferrersThenDelete(referral_list);
+
+  LogStartupMetrics();
 }
 
 //-----------------------------------------------------------------------------
@@ -1172,6 +1174,21 @@ GURL Predictor::GetHSTSRedirectOnIOThread(const GURL& url) {
   return url.ReplaceComponents(replacements);
 }
 
+void Predictor::LogStartupMetrics() {
+  size_t total_bytes = 0;
+  for (const auto& referrer : referrers_) {
+    total_bytes += referrer.first.spec().size();
+    total_bytes += sizeof(Referrer);
+    for (const auto& subresource : referrer.second) {
+      total_bytes += subresource.first.spec().size();
+      total_bytes += sizeof(ReferrerValue);
+    }
+  }
+  UMA_HISTOGRAM_CUSTOM_COUNTS("Net.Predictor.Startup.DBSize", total_bytes, 1,
+                              10 * 1000 * 1000, 50);
+}
+
+
 // ---------------------- End IO methods. -------------------------------------
 
 //-----------------------------------------------------------------------------