[net/dns] Instrument DnsConfigService to measure performance and failures.

net/base/host_resolver_impl.cc

Index: net/base/host_resolver_impl.cc
diff --git a/net/base/host_resolver_impl.cc b/net/base/host_resolver_impl.cc
index 811a002c599b73a9e4ef7a4b264b41016687bce9..d184de7fc565313bc383e13a97c30d1c17feba3d 100644
--- a/net/base/host_resolver_impl.cc
+++ b/net/base/host_resolver_impl.cc
@@ -1355,9 +1355,8 @@ class HostResolverImpl::Job : public PrioritizedDispatcher::Job {
       SetPortOnAddressList(requests_->front()->info().port(), &list);
       // Record this histogram here, when we know the system has a valid DNS
       // configuration.
-      UMA_HISTOGRAM_ENUMERATION("AsyncDNS.HaveDnsConfig",
-                                resolver_->received_dns_config_ ? 1 : 0,
-                                2);
+      UMA_HISTOGRAM_BOOLEAN("AsyncDNS.HaveDnsConfig",
+                            resolver_->received_dns_config_);
     }
 
     if ((net_error != ERR_ABORTED) &&