Add histograms and NetLog for host cache persistence

components/cronet/android/cronet_url_request_context_adapter.cc

Index: components/cronet/android/cronet_url_request_context_adapter.cc
diff --git a/components/cronet/android/cronet_url_request_context_adapter.cc b/components/cronet/android/cronet_url_request_context_adapter.cc
index 510ab011c1cc79bf6de577982c37c7c59351a7db..36061c83ad85999d094590e13c4cebf8c8bfb603 100644
--- a/components/cronet/android/cronet_url_request_context_adapter.cc
+++ b/components/cronet/android/cronet_url_request_context_adapter.cc
@@ -663,7 +663,11 @@ void CronetURLRequestContextAdapter::InitializeOnNetworkThread(
     if (config->enable_host_cache_persistence) {
       registry->RegisterListPref(kHostCachePref);
     }
+    base::TimeTicks prefs_init_start = base::TimeTicks::Now();
     pref_service_ = factory.Create(registry.get());
+    base::TimeTicks prefs_init_end = base::TimeTicks::Now();
+    UMA_HISTOGRAM_TIMES("Net.Cronet.PrefsInitTime",
+                        prefs_init_end - prefs_init_start);

[pauljensen, 2017/06/28 14:12:01]

{
    SCOPED_UMA_HISTOGRAM_TIMER("Net.Cronet.PrefsInitTime");
    pref_service_ = factory.Create(registry.get());
}

[mgersh, 2017/06/28 14:21:08]

Done.

 
     // Set up the HttpServerPropertiesManager.
     std::unique_ptr<net::HttpServerPropertiesManager>
@@ -727,7 +731,8 @@ void CronetURLRequestContextAdapter::InitializeOnNetworkThread(
         base::MakeUnique<HostCachePersistenceManager>(
             host_cache, pref_service_.get(), kHostCachePref,
             base::TimeDelta::FromMilliseconds(
-                config->host_cache_persistence_delay_ms));
+                config->host_cache_persistence_delay_ms),
+            g_net_log.Get().net_log());
   }
 
   context_->set_check_cleartext_permitted(true);