Avoid initial NetworkChangeNotifier OnDNSChanged() signal on Android

net/dns/host_resolver_impl.cc

 // Copyright (c) 2012 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/dns/host_resolver_impl.h"
 
 #if defined(OS_WIN)
 #include <Winsock2.h>
 #elif defined(OS_POSIX)
 #include <netdb.h>
@@ skipping 2271 matching lines @@
   probe_weak_ptr_factory_.InvalidateWeakPtrs();
   if (cache_.get())
     cache_->clear();
 #if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_ANDROID)
   new LoopbackProbeJob(probe_weak_ptr_factory_.GetWeakPtr());
 #endif
   AbortAllInProgressJobs();
   // |this| may be deleted inside AbortAllInProgressJobs().
 }
 
+void HostResolverImpl::OnInitialDNSConfigRead() {
+  UpdateDNSConfig(false);
+}
+
 void HostResolverImpl::OnDNSChanged() {
+  UpdateDNSConfig(true);
+}
+
+void HostResolverImpl::UpdateDNSConfig(bool config_changed) {
   DnsConfig dns_config;
   NetworkChangeNotifier::GetDnsConfig(&dns_config);
 
   if (net_log_) {
     net_log_->AddGlobalEntry(
         NetLog::TYPE_DNS_CONFIG_CHANGED,
         base::Bind(&NetLogDnsConfigCallback, &dns_config));
   }
 
   // TODO(szym): Remove once http://crbug.com/137914 is resolved.
   received_dns_config_ = dns_config.IsValid();
   // Conservatively assume local IPv6 is needed when DnsConfig is not valid.
   use_local_ipv6_ = !dns_config.IsValid() || dns_config.use_local_ipv6;
 
   num_dns_failures_ = 0;
 
   // We want a new DnsSession in place, before we Abort running Jobs, so that
   // the newly started jobs use the new config.
   if (dns_client_.get()) {
     dns_client_->SetConfig(dns_config);
-    if (dns_client_->GetConfig())
+    if (dns_client_->GetConfig()) {
       UMA_HISTOGRAM_BOOLEAN("AsyncDNS.DnsClientEnabled", true);
+      // If we just switched DnsClients, restart jobs using new resolver.
+      // TODO(pauljensen): Is this necessary?
+      config_changed = true;
+    }
   }
 
-  // If the DNS server has changed, existing cached info could be wrong so we
-  // have to drop our internal cache :( Note that OS level DNS caches, such
-  // as NSCD's cache should be dropped automatically by the OS when
-  // resolv.conf changes so we don't need to do anything to clear that cache.
-  if (cache_.get())
-    cache_->clear();
+  if (config_changed) {
+    // If the DNS server has changed, existing cached info could be wrong so we
+    // have to drop our internal cache :( Note that OS level DNS caches, such
+    // as NSCD's cache should be dropped automatically by the OS when
+    // resolv.conf changes so we don't need to do anything to clear that cache.
+    if (cache_.get())
+      cache_->clear();
 
-  // Life check to bail once |this| is deleted.
-  base::WeakPtr<HostResolverImpl> self = weak_ptr_factory_.GetWeakPtr();
+    // Life check to bail once |this| is deleted.
+    base::WeakPtr<HostResolverImpl> self = weak_ptr_factory_.GetWeakPtr();
 
-  // Existing jobs will have been sent to the original server so they need to
-  // be aborted.
-  AbortAllInProgressJobs();
+    // Existing jobs will have been sent to the original server so they need to
+    // be aborted.
+    AbortAllInProgressJobs();
 
-  // |this| may be deleted inside AbortAllInProgressJobs().
-  if (self.get())
-    TryServingAllJobsFromHosts();
+    // |this| may be deleted inside AbortAllInProgressJobs().
+    if (self.get())
+      TryServingAllJobsFromHosts();
+  }
 }
 
 bool HostResolverImpl::HaveDnsConfig() const {
   // Use DnsClient only if it's fully configured and there is no override by
   // ScopedDefaultHostResolverProc.
   // The alternative is to use NetworkChangeNotifier to override DnsConfig,
   // but that would introduce construction order requirements for NCN and SDHRP.
   return (dns_client_.get() != NULL) && (dns_client_->GetConfig() != NULL) &&
          !(proc_params_.resolver_proc.get() == NULL &&
            HostResolverProc::GetDefault() != NULL);
@@ skipping 33 matching lines @@
     dns_client_->SetConfig(dns_config);
     num_dns_failures_ = 0;
     if (dns_client_->GetConfig())
       UMA_HISTOGRAM_BOOLEAN("AsyncDNS.DnsClientEnabled", true);
   }
 
   AbortDnsTasks();
 }
 
 }  // namespace net