Add a histogram to track how many server configs has been persisted

net/http/http_server_properties_manager.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/http/http_server_properties_manager.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/memory/ptr_util.h"
@@ skipping 757 matching lines @@
   // preferences.
   UMA_HISTOGRAM_COUNTS("Net.CountOfAlternateProtocolServers",
                        alternative_service_map->size());
   http_server_properties_impl_->SetAlternativeServiceServers(
       alternative_service_map);
 
   http_server_properties_impl_->SetSupportsQuic(last_quic_address);
 
   http_server_properties_impl_->SetServerNetworkStats(server_network_stats_map);
 
+  UMA_HISTOGRAM_COUNTS("Net.CountOfQuicServerInfos",

[Alexei Svitkine (slow), 2017/02/23 18:23:41]

Nit: We now recommend to use UMA_HISTOGRAM_COUNTS_<max>() macros instead.

UMA_HISTOGRAM_COUNTS() corresponds to UMA_HISTOGRAM_COUNTS_1M() - so if that's
appropriate use that, but I suspect in this case you might have better results
with a smaller maximum like 10k or something.

[Zhongyi Shi, 2017/02/23 20:36:22]

Done.

+                       quic_server_info_map->size());
+
   http_server_properties_impl_->SetQuicServerInfoMap(quic_server_info_map);
 
   // Update the prefs with what we have read (delete all corrupted prefs).
   if (detected_corrupted_prefs)
     ScheduleUpdatePrefsOnNetworkThread(DETECTED_CORRUPTED_PREFS);
 }
 
 //
 // Update Preferences with data from the cached data.
 //
@@ skipping 334 matching lines @@
   if (!setting_prefs_)
     ScheduleUpdateCacheOnPrefThread();
 }
 
 void HttpServerPropertiesManager::SetInitialized() {
   DCHECK(network_task_runner_->RunsTasksOnCurrentThread());
   is_initialized_ = true;
 }
 
 }  // namespace net