Add an entry in histograms.xml for SafeBrowsing.V4UpdateHttpResponseOrErrorCode

components/safe_browsing_db/v4_update_protocol_manager.cc

Index: components/safe_browsing_db/v4_update_protocol_manager.cc
diff --git a/components/safe_browsing_db/v4_update_protocol_manager.cc b/components/safe_browsing_db/v4_update_protocol_manager.cc
index 483d57871f50d366d9bb69eb886b3e848f3b7bc6..b6a08e497ca74c58e7189e3f161c4964addb2543 100644
--- a/components/safe_browsing_db/v4_update_protocol_manager.cc
+++ b/components/safe_browsing_db/v4_update_protocol_manager.cc
@@ -9,6 +9,7 @@
 #include "base/base64.h"
 #include "base/macros.h"
 #include "base/metrics/histogram_macros.h"
+#include "base/metrics/sparse_histogram.h"
 #include "base/rand_util.h"
 #include "base/timer/timer.h"
 #include "components/safe_browsing_db/safebrowsing.pb.h"
@@ -328,6 +329,10 @@ void V4UpdateProtocolManager::OnURLFetchComplete(
 
     if (status.status() == net::URLRequestStatus::FAILED) {
       RecordUpdateResult(V4OperationResult::NETWORK_ERROR);
+      // Negate the error value since it is negative, see:
+      // net/base/net_error_list.h
+      UMA_HISTOGRAM_SPARSE_SLOWLY("SafeBrowsing.V4UpdateNetworkError",

[Nathan Parker, 2016/06/02 20:56:31]

How about recording both the network error or status, like
https://code.google.com/p/chromium/codesearch#chromium/src/chrome/browser/saf...

[vakh (use Gerrit instead), 2016/06/02 21:43:27]

Done.

+                                  -status.error());
     } else {
       RecordUpdateResult(V4OperationResult::HTTP_ERROR);
     }