AlternativeServiceServers - Added couple of histograms to measure if

net/http/http_server_properties_impl.cc

Index: net/http/http_server_properties_impl.cc
diff --git a/net/http/http_server_properties_impl.cc b/net/http/http_server_properties_impl.cc
index 77968ff7d6105a653b6f7746fee0713fe7e9a7ad..567f182f041bff5a36cdf3a44a0d2e80a572473b 100644
--- a/net/http/http_server_properties_impl.cc
+++ b/net/http/http_server_properties_impl.cc
@@ -10,6 +10,7 @@
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/single_thread_task_runner.h"
 #include "base/stl_util.h"
 #include "base/strings/string_util.h"
@@ -56,6 +57,16 @@ void HttpServerPropertiesImpl::InitializeSpdyServers(
 
 void HttpServerPropertiesImpl::InitializeAlternativeServiceServers(
     AlternativeServiceMap* alternative_service_map) {
+  int32 size_diff =
+      alternative_service_map->size() - alternative_service_map_.size();
+  if (size_diff > 0) {
+    UMA_HISTOGRAM_COUNTS("Net.AlternativeServiceServers.MorePrefsEntries",
+                         size_diff);
+  } else {

[Alexei Svitkine (slow), 2015/12/18 19:58:48]

Should you check that size_diff isn't 0? It's fine to log it for 0 too, but in
that case you should expand the histogram description to mention that case.

[ramant (doing other things), 2015/12/18 21:34:55]

Good point. Changed the histogram name and description.

Done.

+    UMA_HISTOGRAM_COUNTS("Net.AlternativeServiceServers.MoreCacheEntries",
+                         -size_diff);
+  }
+
   // Add the entries from persisted data.
   for (AlternativeServiceMap::reverse_iterator input_it =
            alternative_service_map->rbegin();