Move service_discovery_client_impl.* into chrome/common.

It's need to be used by utility and browser processes.

BUG=349645

Review URL: https://codereview.chromium.org/256923003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@266487 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 1558 insertions, 0 deletions

diff --git a/chrome/common/local_discovery/local_domain_resolver_unittest.cc b/chrome/common/local_discovery/local_domain_resolver_unittest.cc
new file mode 100644
index 0000000..cc65ab3
--- /dev/null
+++ b/chrome/common/local_discovery/local_domain_resolver_unittest.cc
@@ -0,0 +1,183 @@
+// 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 "chrome/common/local_discovery/service_discovery_client_impl.h"
+#include "net/dns/mdns_client_impl.h"
+#include "net/dns/mock_mdns_socket_factory.h"
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+using ::testing::_;
+
+namespace local_discovery {
+
+namespace {
+
+const uint8 kSamplePacketA[] = {
+  // Header
+  0x00, 0x00,               // ID is zeroed out
+  0x81, 0x80,               // Standard query response, RA, no error
+  0x00, 0x00,               // No questions (for simplicity)
+  0x00, 0x01,               // 1 RR (answers)
+  0x00, 0x00,               // 0 authority RRs
+  0x00, 0x00,               // 0 additional RRs
+
+  0x07, 'm', 'y', 'h', 'e', 'l', 'l', 'o',
+  0x05, 'l', 'o', 'c', 'a', 'l',
+  0x00,
+  0x00, 0x01,        // TYPE is A.
+  0x00, 0x01,        // CLASS is IN.
+  0x00, 0x00,        // TTL (4 bytes) is 16 seconds.
+  0x00, 0x10,
+  0x00, 0x04,        // RDLENGTH is 4 bytes.
+  0x01, 0x02,
+  0x03, 0x04,
+};
+
+const uint8 kSamplePacketAAAA[] = {
+  // Header
+  0x00, 0x00,               // ID is zeroed out
+  0x81, 0x80,               // Standard query response, RA, no error
+  0x00, 0x00,               // No questions (for simplicity)
+  0x00, 0x01,               // 1 RR (answers)
+  0x00, 0x00,               // 0 authority RRs
+  0x00, 0x00,               // 0 additional RRs
+
+  0x07, 'm', 'y', 'h', 'e', 'l', 'l', 'o',
+  0x05, 'l', 'o', 'c', 'a', 'l',
+  0x00,
+  0x00, 0x1C,        // TYPE is AAAA.
+  0x00, 0x01,        // CLASS is IN.
+  0x00, 0x00,        // TTL (4 bytes) is 16 seconds.
+  0x00, 0x10,
+  0x00, 0x10,        // RDLENGTH is 4 bytes.
+  0x00, 0x0A, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00,
+  0x00, 0x01, 0x00, 0x02,
+  0x00, 0x03, 0x00, 0x04,
+};
+
+class LocalDomainResolverTest : public testing::Test {
+ public:
+  virtual void SetUp() OVERRIDE {
+    mdns_client_.StartListening(&socket_factory_);
+  }
+
+  std::string IPAddressToStringWithEmpty(const net::IPAddressNumber& address) {
+    if (address.empty()) return "";
+    return net::IPAddressToString(address);
+  }
+
+  void AddressCallback(bool resolved,
+                       const net::IPAddressNumber& address_ipv4,
+                       const net::IPAddressNumber& address_ipv6) {
+      AddressCallbackInternal(resolved,
+                              IPAddressToStringWithEmpty(address_ipv4),
+                              IPAddressToStringWithEmpty(address_ipv6));
+  }
+
+  void RunFor(base::TimeDelta time_period) {
+    base::CancelableCallback<void()> callback(base::Bind(
+        &base::MessageLoop::Quit,
+        base::Unretained(base::MessageLoop::current())));
+    base::MessageLoop::current()->PostDelayedTask(
+        FROM_HERE, callback.callback(), time_period);
+
+    base::MessageLoop::current()->Run();
+    callback.Cancel();
+  }
+
+  MOCK_METHOD3(AddressCallbackInternal,
+               void(bool resolved,
+                    std::string address_ipv4,
+                    std::string address_ipv6));
+
+  net::MockMDnsSocketFactory socket_factory_;
+  net::MDnsClientImpl mdns_client_;
+  base::MessageLoop message_loop_;
+};
+
+TEST_F(LocalDomainResolverTest, ResolveDomainA) {
+  LocalDomainResolverImpl resolver(
+      "myhello.local", net::ADDRESS_FAMILY_IPV4,
+      base::Bind(&LocalDomainResolverTest::AddressCallback,
+                 base::Unretained(this)), &mdns_client_);
+
+  EXPECT_CALL(socket_factory_, OnSendTo(_)).Times(2);  // Twice per query
+
+  resolver.Start();
+
+  EXPECT_CALL(*this, AddressCallbackInternal(true, "1.2.3.4", ""));
+
+  socket_factory_.SimulateReceive(kSamplePacketA, sizeof(kSamplePacketA));
+}
+
+TEST_F(LocalDomainResolverTest, ResolveDomainAAAA) {
+  LocalDomainResolverImpl resolver(
+      "myhello.local", net::ADDRESS_FAMILY_IPV6,
+      base::Bind(&LocalDomainResolverTest::AddressCallback,
+                 base::Unretained(this)), &mdns_client_);
+
+  EXPECT_CALL(socket_factory_, OnSendTo(_)).Times(2);  // Twice per query
+
+  resolver.Start();
+
+  EXPECT_CALL(*this, AddressCallbackInternal(true, "", "a::1:2:3:4"));
+
+  socket_factory_.SimulateReceive(kSamplePacketAAAA, sizeof(kSamplePacketAAAA));
+}
+
+TEST_F(LocalDomainResolverTest, ResolveDomainAnyOneAvailable) {
+  LocalDomainResolverImpl resolver(
+      "myhello.local", net::ADDRESS_FAMILY_UNSPECIFIED,
+      base::Bind(&LocalDomainResolverTest::AddressCallback,
+                 base::Unretained(this)), &mdns_client_);
+
+  EXPECT_CALL(socket_factory_, OnSendTo(_)).Times(4);  // Twice per query
+
+  resolver.Start();
+
+  socket_factory_.SimulateReceive(kSamplePacketAAAA, sizeof(kSamplePacketAAAA));
+
+  EXPECT_CALL(*this, AddressCallbackInternal(true, "", "a::1:2:3:4"));
+
+  RunFor(base::TimeDelta::FromMilliseconds(150));
+}
+
+
+TEST_F(LocalDomainResolverTest, ResolveDomainAnyBothAvailable) {
+  LocalDomainResolverImpl resolver(
+      "myhello.local", net::ADDRESS_FAMILY_UNSPECIFIED,
+      base::Bind(&LocalDomainResolverTest::AddressCallback,
+                 base::Unretained(this)), &mdns_client_);
+
+  EXPECT_CALL(socket_factory_, OnSendTo(_)).Times(4);  // Twice per query
+
+  resolver.Start();
+
+  EXPECT_CALL(*this, AddressCallbackInternal(true, "1.2.3.4", "a::1:2:3:4"));
+
+  socket_factory_.SimulateReceive(kSamplePacketAAAA, sizeof(kSamplePacketAAAA));
+
+  socket_factory_.SimulateReceive(kSamplePacketA, sizeof(kSamplePacketA));
+}
+
+TEST_F(LocalDomainResolverTest, ResolveDomainNone) {
+  LocalDomainResolverImpl resolver(
+      "myhello.local", net::ADDRESS_FAMILY_UNSPECIFIED,
+      base::Bind(&LocalDomainResolverTest::AddressCallback,
+                 base::Unretained(this)), &mdns_client_);
+
+  EXPECT_CALL(socket_factory_, OnSendTo(_)).Times(4);  // Twice per query
+
+  resolver.Start();
+
+  EXPECT_CALL(*this, AddressCallbackInternal(false, "", ""));
+
+  RunFor(base::TimeDelta::FromSeconds(4));
+}
+
+}  // namespace
+
+}  // namespace local_discovery
diff --git a/chrome/common/local_discovery/service_discovery_client_impl.cc b/chrome/common/local_discovery/service_discovery_client_impl.cc
new file mode 100644
index 0000000..c86f726
--- /dev/null
+++ b/chrome/common/local_discovery/service_discovery_client_impl.cc
@@ -0,0 +1,584 @@
+// 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 <utility>
+
+#include "base/logging.h"
+#include "base/memory/singleton.h"
+#include "base/message_loop/message_loop_proxy.h"
+#include "base/stl_util.h"
+#include "chrome/common/local_discovery/service_discovery_client_impl.h"
+#include "net/dns/dns_protocol.h"
+#include "net/dns/record_rdata.h"
+
+namespace local_discovery {
+
+namespace {
+// TODO(noamsml): Make this configurable through the LocalDomainResolver
+// interface.
+const int kLocalDomainSecondAddressTimeoutMs = 100;
+
+const int kInitialRequeryTimeSeconds = 1;
+const int kMaxRequeryTimeSeconds = 2; // Time for last requery
+}
+
+ServiceDiscoveryClientImpl::ServiceDiscoveryClientImpl(
+    net::MDnsClient* mdns_client) : mdns_client_(mdns_client) {
+}
+
+ServiceDiscoveryClientImpl::~ServiceDiscoveryClientImpl() {
+}
+
+scoped_ptr<ServiceWatcher> ServiceDiscoveryClientImpl::CreateServiceWatcher(
+    const std::string& service_type,
+    const ServiceWatcher::UpdatedCallback& callback) {
+  return scoped_ptr<ServiceWatcher>(new ServiceWatcherImpl(
+      service_type, callback, mdns_client_));
+}
+
+scoped_ptr<ServiceResolver> ServiceDiscoveryClientImpl::CreateServiceResolver(
+    const std::string& service_name,
+    const ServiceResolver::ResolveCompleteCallback& callback) {
+  return scoped_ptr<ServiceResolver>(new ServiceResolverImpl(
+      service_name, callback, mdns_client_));
+}
+
+scoped_ptr<LocalDomainResolver>
+ServiceDiscoveryClientImpl::CreateLocalDomainResolver(
+      const std::string& domain,
+      net::AddressFamily address_family,
+      const LocalDomainResolver::IPAddressCallback& callback) {
+  return scoped_ptr<LocalDomainResolver>(new LocalDomainResolverImpl(
+      domain, address_family, callback, mdns_client_));
+}
+
+ServiceWatcherImpl::ServiceWatcherImpl(
+    const std::string& service_type,
+    const ServiceWatcher::UpdatedCallback& callback,
+    net::MDnsClient* mdns_client)
+    : service_type_(service_type), callback_(callback), started_(false),
+      actively_refresh_services_(false), mdns_client_(mdns_client) {
+}
+
+void ServiceWatcherImpl::Start() {
+  DCHECK(!started_);
+  listener_ = mdns_client_->CreateListener(
+      net::dns_protocol::kTypePTR, service_type_, this);
+  started_ = listener_->Start();
+  if (started_)
+    ReadCachedServices();
+}
+
+ServiceWatcherImpl::~ServiceWatcherImpl() {
+}
+
+void ServiceWatcherImpl::DiscoverNewServices(bool force_update) {
+  DCHECK(started_);
+  if (force_update)
+    services_.clear();
+  SendQuery(kInitialRequeryTimeSeconds, force_update);
+}
+
+void ServiceWatcherImpl::SetActivelyRefreshServices(
+    bool actively_refresh_services) {
+  DCHECK(started_);
+  actively_refresh_services_ = actively_refresh_services;
+
+  for (ServiceListenersMap::iterator i = services_.begin();
+       i != services_.end(); i++) {
+    i->second->SetActiveRefresh(actively_refresh_services);
+  }
+}
+
+void ServiceWatcherImpl::ReadCachedServices() {
+  DCHECK(started_);
+  CreateTransaction(false /*network*/, true /*cache*/, false /*force refresh*/,
+                    &transaction_cache_);
+}
+
+bool ServiceWatcherImpl::CreateTransaction(
+    bool network, bool cache, bool force_refresh,
+    scoped_ptr<net::MDnsTransaction>* transaction) {
+  int transaction_flags = 0;
+  if (network)
+    transaction_flags |= net::MDnsTransaction::QUERY_NETWORK;
+
+  if (cache)
+    transaction_flags |= net::MDnsTransaction::QUERY_CACHE;
+
+  // TODO(noamsml): Add flag for force_refresh when supported.
+
+  if (transaction_flags) {
+    *transaction = mdns_client_->CreateTransaction(
+        net::dns_protocol::kTypePTR, service_type_, transaction_flags,
+        base::Bind(&ServiceWatcherImpl::OnTransactionResponse,
+                   base::Unretained(this), transaction));
+    return (*transaction)->Start();
+  }
+
+  return true;
+}
+
+std::string ServiceWatcherImpl::GetServiceType() const {
+  return listener_->GetName();
+}
+
+void ServiceWatcherImpl::OnRecordUpdate(
+    net::MDnsListener::UpdateType update,
+    const net::RecordParsed* record) {
+  DCHECK(started_);
+  if (record->type() == net::dns_protocol::kTypePTR) {
+    DCHECK(record->name() == GetServiceType());
+    const net::PtrRecordRdata* rdata = record->rdata<net::PtrRecordRdata>();
+
+    switch (update) {
+      case net::MDnsListener::RECORD_ADDED:
+        AddService(rdata->ptrdomain());
+        break;
+      case net::MDnsListener::RECORD_CHANGED:
+        NOTREACHED();
+        break;
+      case net::MDnsListener::RECORD_REMOVED:
+        RemovePTR(rdata->ptrdomain());
+        break;
+    }
+  } else {
+    DCHECK(record->type() == net::dns_protocol::kTypeSRV ||
+           record->type() == net::dns_protocol::kTypeTXT);
+    DCHECK(services_.find(record->name()) != services_.end());
+
+    if (record->type() == net::dns_protocol::kTypeSRV) {
+      if (update == net::MDnsListener::RECORD_REMOVED) {
+        RemoveSRV(record->name());
+      } else if (update == net::MDnsListener::RECORD_ADDED) {
+        AddSRV(record->name());
+      }
+    }
+
+    // If this is the first time we see an SRV record, do not send
+    // an UPDATE_CHANGED.
+    if (record->type() != net::dns_protocol::kTypeSRV ||
+        update != net::MDnsListener::RECORD_ADDED) {
+      DeferUpdate(UPDATE_CHANGED, record->name());
+    }
+  }
+}
+
+void ServiceWatcherImpl::OnCachePurged() {
+  // Not yet implemented.
+}
+
+void ServiceWatcherImpl::OnTransactionResponse(
+    scoped_ptr<net::MDnsTransaction>* transaction,
+    net::MDnsTransaction::Result result,
+    const net::RecordParsed* record) {
+  DCHECK(started_);
+  if (result == net::MDnsTransaction::RESULT_RECORD) {
+    const net::PtrRecordRdata* rdata = record->rdata<net::PtrRecordRdata>();
+    DCHECK(rdata);
+    AddService(rdata->ptrdomain());
+  } else if (result == net::MDnsTransaction::RESULT_DONE) {
+    transaction->reset();
+  }
+
+  // Do nothing for NSEC records. It is an error for hosts to broadcast an NSEC
+  // record for PTR records on any name.
+}
+
+ServiceWatcherImpl::ServiceListeners::ServiceListeners(
+    const std::string& service_name,
+    ServiceWatcherImpl* watcher,
+    net::MDnsClient* mdns_client)
+    : service_name_(service_name), mdns_client_(mdns_client),
+      update_pending_(false), has_ptr_(true), has_srv_(false) {
+  srv_listener_ = mdns_client->CreateListener(
+      net::dns_protocol::kTypeSRV, service_name, watcher);
+  txt_listener_ = mdns_client->CreateListener(
+      net::dns_protocol::kTypeTXT, service_name, watcher);
+}
+
+ServiceWatcherImpl::ServiceListeners::~ServiceListeners() {
+}
+
+bool ServiceWatcherImpl::ServiceListeners::Start() {
+  if (!srv_listener_->Start())
+    return false;
+  return txt_listener_->Start();
+}
+
+void ServiceWatcherImpl::ServiceListeners::SetActiveRefresh(
+    bool active_refresh) {
+  srv_listener_->SetActiveRefresh(active_refresh);
+
+  if (active_refresh && !has_srv_) {
+    DCHECK(has_ptr_);
+    srv_transaction_ = mdns_client_->CreateTransaction(
+        net::dns_protocol::kTypeSRV, service_name_,
+        net::MDnsTransaction::SINGLE_RESULT |
+        net::MDnsTransaction::QUERY_CACHE | net::MDnsTransaction::QUERY_NETWORK,
+        base::Bind(&ServiceWatcherImpl::ServiceListeners::OnSRVRecord,
+                   base::Unretained(this)));
+    srv_transaction_->Start();
+  } else if (!active_refresh) {
+    srv_transaction_.reset();
+  }
+}
+
+void ServiceWatcherImpl::ServiceListeners::OnSRVRecord(
+    net::MDnsTransaction::Result result,
+    const net::RecordParsed* record) {
+  set_has_srv(record != NULL);
+}
+
+void ServiceWatcherImpl::ServiceListeners::set_has_srv(bool has_srv) {
+  has_srv_ = has_srv;
+
+  srv_transaction_.reset();
+}
+
+void ServiceWatcherImpl::AddService(const std::string& service) {
+  DCHECK(started_);
+  std::pair<ServiceListenersMap::iterator, bool> found = services_.insert(
+      make_pair(service, linked_ptr<ServiceListeners>(NULL)));
+
+  if (found.second) {  // Newly inserted.
+    found.first->second = linked_ptr<ServiceListeners>(
+        new ServiceListeners(service, this, mdns_client_));
+    bool success = found.first->second->Start();
+    found.first->second->SetActiveRefresh(actively_refresh_services_);
+    DeferUpdate(UPDATE_ADDED, service);
+
+    DCHECK(success);
+  }
+
+  found.first->second->set_has_ptr(true);
+}
+
+void ServiceWatcherImpl::AddSRV(const std::string& service) {
+  DCHECK(started_);
+
+  ServiceListenersMap::iterator found = services_.find(service);
+  if (found != services_.end()) {
+    found->second->set_has_srv(true);
+  }
+}
+
+void ServiceWatcherImpl::DeferUpdate(ServiceWatcher::UpdateType update_type,
+                                     const std::string& service_name) {
+  ServiceListenersMap::iterator found = services_.find(service_name);
+
+  if (found != services_.end() && !found->second->update_pending()) {
+    found->second->set_update_pending(true);
+    base::MessageLoop::current()->PostTask(
+        FROM_HERE,
+        base::Bind(&ServiceWatcherImpl::DeliverDeferredUpdate, AsWeakPtr(),
+                   update_type, service_name));
+  }
+}
+
+void ServiceWatcherImpl::DeliverDeferredUpdate(
+    ServiceWatcher::UpdateType update_type, const std::string& service_name) {
+  ServiceListenersMap::iterator found = services_.find(service_name);
+
+  if (found != services_.end()) {
+    found->second->set_update_pending(false);
+    if (!callback_.is_null())
+      callback_.Run(update_type, service_name);
+  }
+}
+
+void ServiceWatcherImpl::RemovePTR(const std::string& service) {
+  DCHECK(started_);
+
+  ServiceListenersMap::iterator found = services_.find(service);
+  if (found != services_.end()) {
+    found->second->set_has_ptr(false);
+
+    if (!found->second->has_ptr_or_srv()) {
+      services_.erase(found);
+      if (!callback_.is_null())
+        callback_.Run(UPDATE_REMOVED, service);
+    }
+  }
+}
+
+void ServiceWatcherImpl::RemoveSRV(const std::string& service) {
+  DCHECK(started_);
+
+  ServiceListenersMap::iterator found = services_.find(service);
+  if (found != services_.end()) {
+    found->second->set_has_srv(false);
+
+    if (!found->second->has_ptr_or_srv()) {
+      services_.erase(found);
+      if (!callback_.is_null())
+        callback_.Run(UPDATE_REMOVED, service);
+    }
+  }
+}
+
+void ServiceWatcherImpl::OnNsecRecord(const std::string& name,
+                                      unsigned rrtype) {
+  // Do nothing. It is an error for hosts to broadcast an NSEC record for PTR
+  // on any name.
+}
+
+void ServiceWatcherImpl::ScheduleQuery(int timeout_seconds) {
+  if (timeout_seconds <= kMaxRequeryTimeSeconds) {
+    base::MessageLoop::current()->PostDelayedTask(
+        FROM_HERE,
+        base::Bind(&ServiceWatcherImpl::SendQuery,
+                   AsWeakPtr(),
+                   timeout_seconds * 2 /*next_timeout_seconds*/,
+                   false /*force_update*/),
+        base::TimeDelta::FromSeconds(timeout_seconds));
+  }
+}
+
+void ServiceWatcherImpl::SendQuery(int next_timeout_seconds,
+                                   bool force_update) {
+  CreateTransaction(true /*network*/, false /*cache*/, force_update,
+                    &transaction_network_);
+  ScheduleQuery(next_timeout_seconds);
+}
+
+ServiceResolverImpl::ServiceResolverImpl(
+    const std::string& service_name,
+    const ResolveCompleteCallback& callback,
+    net::MDnsClient* mdns_client)
+    : service_name_(service_name), callback_(callback),
+      metadata_resolved_(false), address_resolved_(false),
+      mdns_client_(mdns_client) {
+}
+
+void ServiceResolverImpl::StartResolving() {
+  address_resolved_ = false;
+  metadata_resolved_ = false;
+  service_staging_ = ServiceDescription();
+  service_staging_.service_name = service_name_;
+
+  if (!CreateTxtTransaction() || !CreateSrvTransaction()) {
+    ServiceNotFound(ServiceResolver::STATUS_REQUEST_TIMEOUT);
+  }
+}
+
+ServiceResolverImpl::~ServiceResolverImpl() {
+}
+
+bool ServiceResolverImpl::CreateTxtTransaction() {
+  txt_transaction_ = mdns_client_->CreateTransaction(
+      net::dns_protocol::kTypeTXT, service_name_,
+      net::MDnsTransaction::SINGLE_RESULT | net::MDnsTransaction::QUERY_CACHE |
+      net::MDnsTransaction::QUERY_NETWORK,
+      base::Bind(&ServiceResolverImpl::TxtRecordTransactionResponse,
+                 AsWeakPtr()));
+  return txt_transaction_->Start();
+}
+
+// TODO(noamsml): quick-resolve for AAAA records.  Since A records tend to be in
+void ServiceResolverImpl::CreateATransaction() {
+  a_transaction_ = mdns_client_->CreateTransaction(
+      net::dns_protocol::kTypeA,
+      service_staging_.address.host(),
+      net::MDnsTransaction::SINGLE_RESULT | net::MDnsTransaction::QUERY_CACHE,
+      base::Bind(&ServiceResolverImpl::ARecordTransactionResponse,
+                 AsWeakPtr()));
+  a_transaction_->Start();
+}
+
+bool ServiceResolverImpl::CreateSrvTransaction() {
+  srv_transaction_ = mdns_client_->CreateTransaction(
+      net::dns_protocol::kTypeSRV, service_name_,
+      net::MDnsTransaction::SINGLE_RESULT | net::MDnsTransaction::QUERY_CACHE |
+      net::MDnsTransaction::QUERY_NETWORK,
+      base::Bind(&ServiceResolverImpl::SrvRecordTransactionResponse,
+                 AsWeakPtr()));
+  return srv_transaction_->Start();
+}
+
+std::string ServiceResolverImpl::GetName() const {
+  return service_name_;
+}
+
+void ServiceResolverImpl::SrvRecordTransactionResponse(
+    net::MDnsTransaction::Result status, const net::RecordParsed* record) {
+  srv_transaction_.reset();
+  if (status == net::MDnsTransaction::RESULT_RECORD) {
+    DCHECK(record);
+    service_staging_.address = RecordToAddress(record);
+    service_staging_.last_seen = record->time_created();
+    CreateATransaction();
+  } else {
+    ServiceNotFound(MDnsStatusToRequestStatus(status));
+  }
+}
+
+void ServiceResolverImpl::TxtRecordTransactionResponse(
+    net::MDnsTransaction::Result status, const net::RecordParsed* record) {
+  txt_transaction_.reset();
+  if (status == net::MDnsTransaction::RESULT_RECORD) {
+    DCHECK(record);
+    service_staging_.metadata = RecordToMetadata(record);
+  } else {
+    service_staging_.metadata = std::vector<std::string>();
+  }
+
+  metadata_resolved_ = true;
+  AlertCallbackIfReady();
+}
+
+void ServiceResolverImpl::ARecordTransactionResponse(
+    net::MDnsTransaction::Result status, const net::RecordParsed* record) {
+  a_transaction_.reset();
+
+  if (status == net::MDnsTransaction::RESULT_RECORD) {
+    DCHECK(record);
+    service_staging_.ip_address = RecordToIPAddress(record);
+  } else {
+    service_staging_.ip_address = net::IPAddressNumber();
+  }
+
+  address_resolved_ = true;
+  AlertCallbackIfReady();
+}
+
+void ServiceResolverImpl::AlertCallbackIfReady() {
+  if (metadata_resolved_ && address_resolved_) {
+    txt_transaction_.reset();
+    srv_transaction_.reset();
+    a_transaction_.reset();
+    if (!callback_.is_null())
+      callback_.Run(STATUS_SUCCESS, service_staging_);
+  }
+}
+
+void ServiceResolverImpl::ServiceNotFound(
+    ServiceResolver::RequestStatus status) {
+  txt_transaction_.reset();
+  srv_transaction_.reset();
+  a_transaction_.reset();
+  if (!callback_.is_null())
+    callback_.Run(status, ServiceDescription());
+}
+
+ServiceResolver::RequestStatus ServiceResolverImpl::MDnsStatusToRequestStatus(
+    net::MDnsTransaction::Result status) const {
+  switch (status) {
+    case net::MDnsTransaction::RESULT_RECORD:
+      return ServiceResolver::STATUS_SUCCESS;
+    case net::MDnsTransaction::RESULT_NO_RESULTS:
+      return ServiceResolver::STATUS_REQUEST_TIMEOUT;
+    case net::MDnsTransaction::RESULT_NSEC:
+      return ServiceResolver::STATUS_KNOWN_NONEXISTENT;
+    case net::MDnsTransaction::RESULT_DONE:  // Pass through.
+    default:
+      NOTREACHED();
+      return ServiceResolver::STATUS_REQUEST_TIMEOUT;
+  }
+}
+
+const std::vector<std::string>& ServiceResolverImpl::RecordToMetadata(
+    const net::RecordParsed* record) const {
+  DCHECK(record->type() == net::dns_protocol::kTypeTXT);
+  const net::TxtRecordRdata* txt_rdata = record->rdata<net::TxtRecordRdata>();
+  DCHECK(txt_rdata);
+  return txt_rdata->texts();
+}
+
+net::HostPortPair ServiceResolverImpl::RecordToAddress(
+    const net::RecordParsed* record) const {
+  DCHECK(record->type() == net::dns_protocol::kTypeSRV);
+  const net::SrvRecordRdata* srv_rdata = record->rdata<net::SrvRecordRdata>();
+  DCHECK(srv_rdata);
+  return net::HostPortPair(srv_rdata->target(), srv_rdata->port());
+}
+
+const net::IPAddressNumber& ServiceResolverImpl::RecordToIPAddress(
+    const net::RecordParsed* record) const {
+  DCHECK(record->type() == net::dns_protocol::kTypeA);
+  const net::ARecordRdata* a_rdata = record->rdata<net::ARecordRdata>();
+  DCHECK(a_rdata);
+  return a_rdata->address();
+}
+
+LocalDomainResolverImpl::LocalDomainResolverImpl(
+    const std::string& domain,
+    net::AddressFamily address_family,
+    const IPAddressCallback& callback,
+    net::MDnsClient* mdns_client)
+    : domain_(domain), address_family_(address_family), callback_(callback),
+      transactions_finished_(0), mdns_client_(mdns_client) {
+}
+
+LocalDomainResolverImpl::~LocalDomainResolverImpl() {
+  timeout_callback_.Cancel();
+}
+
+void LocalDomainResolverImpl::Start() {
+  if (address_family_ == net::ADDRESS_FAMILY_IPV4 ||
+      address_family_ == net::ADDRESS_FAMILY_UNSPECIFIED) {
+    transaction_a_ = CreateTransaction(net::dns_protocol::kTypeA);
+    transaction_a_->Start();
+  }
+
+  if (address_family_ == net::ADDRESS_FAMILY_IPV6 ||
+      address_family_ == net::ADDRESS_FAMILY_UNSPECIFIED) {
+    transaction_aaaa_ = CreateTransaction(net::dns_protocol::kTypeAAAA);
+    transaction_aaaa_->Start();
+  }
+}
+
+scoped_ptr<net::MDnsTransaction> LocalDomainResolverImpl::CreateTransaction(
+    uint16 type) {
+  return mdns_client_->CreateTransaction(
+      type, domain_, net::MDnsTransaction::SINGLE_RESULT |
+                     net::MDnsTransaction::QUERY_CACHE |
+                     net::MDnsTransaction::QUERY_NETWORK,
+      base::Bind(&LocalDomainResolverImpl::OnTransactionComplete,
+                 base::Unretained(this)));
+}
+
+void LocalDomainResolverImpl::OnTransactionComplete(
+    net::MDnsTransaction::Result result, const net::RecordParsed* record) {
+  transactions_finished_++;
+
+  if (result == net::MDnsTransaction::RESULT_RECORD) {
+    if (record->type() == net::dns_protocol::kTypeA) {
+      const net::ARecordRdata* rdata = record->rdata<net::ARecordRdata>();
+      address_ipv4_ = rdata->address();
+    } else {
+      DCHECK_EQ(net::dns_protocol::kTypeAAAA, record->type());
+      const net::AAAARecordRdata* rdata = record->rdata<net::AAAARecordRdata>();
+      address_ipv6_ = rdata->address();
+    }
+  }
+
+  if (transactions_finished_ == 1 &&
+      address_family_ == net::ADDRESS_FAMILY_UNSPECIFIED) {
+    timeout_callback_.Reset(base::Bind(
+        &LocalDomainResolverImpl::SendResolvedAddresses,
+        base::Unretained(this)));
+
+    base::MessageLoop::current()->PostDelayedTask(
+        FROM_HERE,
+        timeout_callback_.callback(),
+        base::TimeDelta::FromMilliseconds(kLocalDomainSecondAddressTimeoutMs));
+  } else if (transactions_finished_ == 2
+      || address_family_ != net::ADDRESS_FAMILY_UNSPECIFIED) {
+    SendResolvedAddresses();
+  }
+}
+
+bool LocalDomainResolverImpl::IsSuccess() {
+  return !address_ipv4_.empty() || !address_ipv6_.empty();
+}
+
+void LocalDomainResolverImpl::SendResolvedAddresses() {
+  transaction_a_.reset();
+  transaction_aaaa_.reset();
+  timeout_callback_.Cancel();
+  callback_.Run(IsSuccess(), address_ipv4_, address_ipv6_);
+}
+
+}  // namespace local_discovery
diff --git a/chrome/common/local_discovery/service_discovery_client_impl.h b/chrome/common/local_discovery/service_discovery_client_impl.h
new file mode 100644
index 0000000..29e42c7
--- /dev/null
+++ b/chrome/common/local_discovery/service_discovery_client_impl.h
@@ -0,0 +1,273 @@
+// 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.
+
+#ifndef CHROME_COMMON_LOCAL_DISCOVERY_SERVICE_DISCOVERY_CLIENT_IMPL_H_
+#define CHROME_COMMON_LOCAL_DISCOVERY_SERVICE_DISCOVERY_CLIENT_IMPL_H_
+
+#include <map>
+#include <string>
+#include <vector>
+
+#include "base/callback.h"
+#include "base/cancelable_callback.h"
+#include "base/memory/linked_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "base/message_loop/message_loop.h"
+#include "chrome/common/local_discovery/service_discovery_client.h"
+#include "net/dns/mdns_client.h"
+
+namespace local_discovery {
+
+class ServiceDiscoveryClientImpl : public ServiceDiscoveryClient {
+ public:
+  // |mdns_client| must outlive the Service Discovery Client.
+  explicit ServiceDiscoveryClientImpl(net::MDnsClient* mdns_client);
+  virtual ~ServiceDiscoveryClientImpl();
+
+  // ServiceDiscoveryClient implementation:
+  virtual scoped_ptr<ServiceWatcher> CreateServiceWatcher(
+      const std::string& service_type,
+      const ServiceWatcher::UpdatedCallback& callback) OVERRIDE;
+
+  virtual scoped_ptr<ServiceResolver> CreateServiceResolver(
+      const std::string& service_name,
+      const ServiceResolver::ResolveCompleteCallback& callback) OVERRIDE;
+
+  virtual scoped_ptr<LocalDomainResolver> CreateLocalDomainResolver(
+      const std::string& domain,
+      net::AddressFamily address_family,
+      const LocalDomainResolver::IPAddressCallback& callback) OVERRIDE;
+
+ private:
+  net::MDnsClient* mdns_client_;
+
+  DISALLOW_COPY_AND_ASSIGN(ServiceDiscoveryClientImpl);
+};
+
+class ServiceWatcherImpl : public ServiceWatcher,
+                           public net::MDnsListener::Delegate,
+                           public base::SupportsWeakPtr<ServiceWatcherImpl> {
+ public:
+  ServiceWatcherImpl(const std::string& service_type,
+                     const ServiceWatcher::UpdatedCallback& callback,
+                     net::MDnsClient* mdns_client);
+  // Listening will automatically stop when the destructor is called.
+  virtual ~ServiceWatcherImpl();
+
+  // ServiceWatcher implementation:
+  virtual void Start() OVERRIDE;
+
+  virtual void DiscoverNewServices(bool force_update) OVERRIDE;
+
+  virtual void SetActivelyRefreshServices(
+      bool actively_refresh_services) OVERRIDE;
+
+  virtual std::string GetServiceType() const OVERRIDE;
+
+  virtual void OnRecordUpdate(net::MDnsListener::UpdateType update,
+                              const net::RecordParsed* record) OVERRIDE;
+
+  virtual void OnNsecRecord(const std::string& name, unsigned rrtype) OVERRIDE;
+
+  virtual void OnCachePurged() OVERRIDE;
+
+  virtual void OnTransactionResponse(
+      scoped_ptr<net::MDnsTransaction>* transaction,
+      net::MDnsTransaction::Result result,
+      const net::RecordParsed* record);
+
+ private:
+  struct ServiceListeners {
+    ServiceListeners(const std::string& service_name,
+                     ServiceWatcherImpl* watcher,
+                     net::MDnsClient* mdns_client);
+    ~ServiceListeners();
+    bool Start();
+    void SetActiveRefresh(bool auto_update);
+
+    void set_update_pending(bool update_pending) {
+      update_pending_ = update_pending;
+    }
+
+    bool update_pending() { return update_pending_; }
+
+    void set_has_ptr(bool has_ptr) {
+      has_ptr_ = has_ptr;
+    }
+
+    void set_has_srv(bool has_srv);
+
+    bool has_ptr_or_srv() { return has_ptr_ || has_srv_; }
+
+   private:
+    void OnSRVRecord(net::MDnsTransaction::Result result,
+                     const net::RecordParsed* record);
+
+    void DoQuerySRV();
+
+    scoped_ptr<net::MDnsListener> srv_listener_;
+    scoped_ptr<net::MDnsListener> txt_listener_;
+    scoped_ptr<net::MDnsTransaction> srv_transaction_;
+
+    std::string service_name_;
+    net::MDnsClient* mdns_client_;
+    bool update_pending_;
+
+    bool has_ptr_;
+    bool has_srv_;
+  };
+
+  typedef std::map<std::string, linked_ptr<ServiceListeners> >
+      ServiceListenersMap;
+
+  void ReadCachedServices();
+  void AddService(const std::string& service);
+  void RemovePTR(const std::string& service);
+  void RemoveSRV(const std::string& service);
+  void AddSRV(const std::string& service);
+  bool CreateTransaction(bool active, bool alert_existing_services,
+                         bool force_refresh,
+                         scoped_ptr<net::MDnsTransaction>* transaction);
+
+  void DeferUpdate(ServiceWatcher::UpdateType update_type,
+                   const std::string& service_name);
+  void DeliverDeferredUpdate(ServiceWatcher::UpdateType update_type,
+                             const std::string& service_name);
+
+  void ScheduleQuery(int timeout_seconds);
+
+  void SendQuery(int next_timeout_seconds, bool force_update);
+
+  std::string service_type_;
+  ServiceListenersMap services_;
+  scoped_ptr<net::MDnsTransaction> transaction_network_;
+  scoped_ptr<net::MDnsTransaction> transaction_cache_;
+  scoped_ptr<net::MDnsListener> listener_;
+
+  ServiceWatcher::UpdatedCallback callback_;
+  bool started_;
+  bool actively_refresh_services_;
+
+  net::MDnsClient* mdns_client_;
+
+  DISALLOW_COPY_AND_ASSIGN(ServiceWatcherImpl);
+};
+
+class ServiceResolverImpl
+    : public ServiceResolver,
+      public base::SupportsWeakPtr<ServiceResolverImpl> {
+ public:
+  ServiceResolverImpl(const std::string& service_name,
+                      const ServiceResolver::ResolveCompleteCallback& callback,
+                      net::MDnsClient* mdns_client);
+
+  virtual ~ServiceResolverImpl();
+
+  // ServiceResolver implementation:
+  virtual void StartResolving() OVERRIDE;
+
+  virtual std::string GetName() const OVERRIDE;
+
+ private:
+  // Respond to transaction finishing for SRV records.
+  void SrvRecordTransactionResponse(net::MDnsTransaction::Result status,
+                                    const net::RecordParsed* record);
+
+  // Respond to transaction finishing for TXT records.
+  void TxtRecordTransactionResponse(net::MDnsTransaction::Result status,
+                                    const net::RecordParsed* record);
+
+  // Respond to transaction finishing for A records.
+  void ARecordTransactionResponse(net::MDnsTransaction::Result status,
+                                  const net::RecordParsed* record);
+
+  void AlertCallbackIfReady();
+
+  void ServiceNotFound(RequestStatus status);
+
+  // Convert a TXT record to a vector of strings (metadata).
+  const std::vector<std::string>& RecordToMetadata(
+      const net::RecordParsed* record) const;
+
+  // Convert an SRV record to a host and port pair.
+  net::HostPortPair RecordToAddress(
+      const net::RecordParsed* record) const;
+
+  // Convert an A record to an IP address.
+  const net::IPAddressNumber& RecordToIPAddress(
+      const net::RecordParsed* record) const;
+
+  // Convert an MDns status to a service discovery status.
+  RequestStatus MDnsStatusToRequestStatus(
+      net::MDnsTransaction::Result status) const;
+
+  bool CreateTxtTransaction();
+  bool CreateSrvTransaction();
+  void CreateATransaction();
+
+  std::string service_name_;
+  ResolveCompleteCallback callback_;
+
+  bool has_resolved_;
+
+  bool metadata_resolved_;
+  bool address_resolved_;
+
+  scoped_ptr<net::MDnsTransaction> txt_transaction_;
+  scoped_ptr<net::MDnsTransaction> srv_transaction_;
+  scoped_ptr<net::MDnsTransaction> a_transaction_;
+
+  ServiceDescription service_staging_;
+
+  net::MDnsClient* mdns_client_;
+
+  DISALLOW_COPY_AND_ASSIGN(ServiceResolverImpl);
+};
+
+class LocalDomainResolverImpl : public LocalDomainResolver {
+ public:
+  LocalDomainResolverImpl(const std::string& domain,
+                          net::AddressFamily address_family,
+                          const IPAddressCallback& callback,
+                          net::MDnsClient* mdns_client);
+  virtual ~LocalDomainResolverImpl();
+
+  virtual void Start() OVERRIDE;
+
+  const std::string& domain() { return domain_; }
+
+ private:
+  void OnTransactionComplete(
+      net::MDnsTransaction::Result result,
+      const net::RecordParsed* record);
+
+  scoped_ptr<net::MDnsTransaction> CreateTransaction(uint16 type);
+
+  bool IsSuccess();
+
+  void SendResolvedAddresses();
+
+  std::string domain_;
+  net::AddressFamily address_family_;
+  IPAddressCallback callback_;
+
+  scoped_ptr<net::MDnsTransaction> transaction_a_;
+  scoped_ptr<net::MDnsTransaction> transaction_aaaa_;
+
+  int transactions_finished_;
+
+  net::MDnsClient* mdns_client_;
+
+  net::IPAddressNumber address_ipv4_;
+  net::IPAddressNumber address_ipv6_;
+
+  base::CancelableCallback<void()> timeout_callback_;
+
+  DISALLOW_COPY_AND_ASSIGN(LocalDomainResolverImpl);
+};
+
+
+}  // namespace local_discovery
+
+#endif  // CHROME_COMMON_LOCAL_DISCOVERY_SERVICE_DISCOVERY_CLIENT_IMPL_H_
diff --git a/chrome/common/local_discovery/service_discovery_client_unittest.cc b/chrome/common/local_discovery/service_discovery_client_unittest.cc
new file mode 100644
index 0000000..5033fbdd
--- /dev/null
+++ b/chrome/common/local_discovery/service_discovery_client_unittest.cc
@@ -0,0 +1,518 @@
+// 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 "base/memory/weak_ptr.h"
+#include "base/run_loop.h"
+#include "chrome/common/local_discovery/service_discovery_client_impl.h"
+#include "net/base/net_errors.h"
+#include "net/dns/dns_protocol.h"
+#include "net/dns/mdns_client_impl.h"
+#include "net/dns/mock_mdns_socket_factory.h"
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+using ::testing::_;
+using ::testing::Invoke;
+using ::testing::StrictMock;
+using ::testing::NiceMock;
+using ::testing::Mock;
+using ::testing::SaveArg;
+using ::testing::SetArgPointee;
+using ::testing::Return;
+using ::testing::Exactly;
+
+namespace local_discovery {
+
+namespace {
+
+const uint8 kSamplePacketPTR[] = {
+  // Header
+  0x00, 0x00,               // ID is zeroed out
+  0x81, 0x80,               // Standard query response, RA, no error
+  0x00, 0x00,               // No questions (for simplicity)
+  0x00, 0x01,               // 1 RR (answers)
+  0x00, 0x00,               // 0 authority RRs
+  0x00, 0x00,               // 0 additional RRs
+
+  0x07, '_', 'p', 'r', 'i', 'v', 'e', 't',
+  0x04, '_', 't', 'c', 'p',
+  0x05, 'l', 'o', 'c', 'a', 'l',
+  0x00,
+  0x00, 0x0c,        // TYPE is PTR.
+  0x00, 0x01,        // CLASS is IN.
+  0x00, 0x00,        // TTL (4 bytes) is 1 second.
+  0x00, 0x01,
+  0x00, 0x08,        // RDLENGTH is 8 bytes.
+  0x05, 'h', 'e', 'l', 'l', 'o',
+  0xc0, 0x0c
+};
+
+const uint8 kSamplePacketSRV[] = {
+  // Header
+  0x00, 0x00,               // ID is zeroed out
+  0x81, 0x80,               // Standard query response, RA, no error
+  0x00, 0x00,               // No questions (for simplicity)
+  0x00, 0x01,               // 1 RR (answers)
+  0x00, 0x00,               // 0 authority RRs
+  0x00, 0x00,               // 0 additional RRs
+
+  0x05, 'h', 'e', 'l', 'l', 'o',
+  0x07, '_', 'p', 'r', 'i', 'v', 'e', 't',
+  0x04, '_', 't', 'c', 'p',
+  0x05, 'l', 'o', 'c', 'a', 'l',
+  0x00,
+  0x00, 0x21,        // TYPE is SRV.
+  0x00, 0x01,        // CLASS is IN.
+  0x00, 0x00,        // TTL (4 bytes) is 1 second.
+  0x00, 0x01,
+  0x00, 0x15,        // RDLENGTH is 21 bytes.
+  0x00, 0x00,
+  0x00, 0x00,
+  0x22, 0xb8,  // port 8888
+  0x07, 'm', 'y', 'h', 'e', 'l', 'l', 'o',
+  0x05, 'l', 'o', 'c', 'a', 'l',
+  0x00,
+};
+
+const uint8 kSamplePacketTXT[] = {
+  // Header
+  0x00, 0x00,               // ID is zeroed out
+  0x81, 0x80,               // Standard query response, RA, no error
+  0x00, 0x00,               // No questions (for simplicity)
+  0x00, 0x01,               // 1 RR (answers)
+  0x00, 0x00,               // 0 authority RRs
+  0x00, 0x00,               // 0 additional RRs
+
+  0x05, 'h', 'e', 'l', 'l', 'o',
+  0x07, '_', 'p', 'r', 'i', 'v', 'e', 't',
+  0x04, '_', 't', 'c', 'p',
+  0x05, 'l', 'o', 'c', 'a', 'l',
+  0x00,
+  0x00, 0x10,        // TYPE is PTR.
+  0x00, 0x01,        // CLASS is IN.
+  0x00, 0x00,        // TTL (4 bytes) is 20 hours, 47 minutes, 48 seconds.
+  0x00, 0x01,
+  0x00, 0x06,        // RDLENGTH is 21 bytes.
+  0x05, 'h', 'e', 'l', 'l', 'o'
+};
+
+const uint8 kSamplePacketSRVA[] = {
+  // Header
+  0x00, 0x00,               // ID is zeroed out
+  0x81, 0x80,               // Standard query response, RA, no error
+  0x00, 0x00,               // No questions (for simplicity)
+  0x00, 0x02,               // 2 RR (answers)
+  0x00, 0x00,               // 0 authority RRs
+  0x00, 0x00,               // 0 additional RRs
+
+  0x05, 'h', 'e', 'l', 'l', 'o',
+  0x07, '_', 'p', 'r', 'i', 'v', 'e', 't',
+  0x04, '_', 't', 'c', 'p',
+  0x05, 'l', 'o', 'c', 'a', 'l',
+  0x00,
+  0x00, 0x21,        // TYPE is SRV.
+  0x00, 0x01,        // CLASS is IN.
+  0x00, 0x00,        // TTL (4 bytes) is 16 seconds.
+  0x00, 0x10,
+  0x00, 0x15,        // RDLENGTH is 21 bytes.
+  0x00, 0x00,
+  0x00, 0x00,
+  0x22, 0xb8,  // port 8888
+  0x07, 'm', 'y', 'h', 'e', 'l', 'l', 'o',
+  0x05, 'l', 'o', 'c', 'a', 'l',
+  0x00,
+
+  0x07, 'm', 'y', 'h', 'e', 'l', 'l', 'o',
+  0x05, 'l', 'o', 'c', 'a', 'l',
+  0x00,
+  0x00, 0x01,        // TYPE is A.
+  0x00, 0x01,        // CLASS is IN.
+  0x00, 0x00,        // TTL (4 bytes) is 16 seconds.
+  0x00, 0x10,
+  0x00, 0x04,        // RDLENGTH is 4 bytes.
+  0x01, 0x02,
+  0x03, 0x04,
+};
+
+const uint8 kSamplePacketPTR2[] = {
+  // Header
+  0x00, 0x00,               // ID is zeroed out
+  0x81, 0x80,               // Standard query response, RA, no error
+  0x00, 0x00,               // No questions (for simplicity)
+  0x00, 0x02,               // 2 RR (answers)
+  0x00, 0x00,               // 0 authority RRs
+  0x00, 0x00,               // 0 additional RRs
+
+  0x07, '_', 'p', 'r', 'i', 'v', 'e', 't',
+  0x04, '_', 't', 'c', 'p',
+  0x05, 'l', 'o', 'c', 'a', 'l',
+  0x00,
+  0x00, 0x0c,        // TYPE is PTR.
+  0x00, 0x01,        // CLASS is IN.
+  0x02, 0x00,        // TTL (4 bytes) is 1 second.
+  0x00, 0x01,
+  0x00, 0x08,        // RDLENGTH is 8 bytes.
+  0x05, 'g', 'd', 'b', 'y', 'e',
+  0xc0, 0x0c,
+
+  0x07, '_', 'p', 'r', 'i', 'v', 'e', 't',
+  0x04, '_', 't', 'c', 'p',
+  0x05, 'l', 'o', 'c', 'a', 'l',
+  0x00,
+  0x00, 0x0c,        // TYPE is PTR.
+  0x00, 0x01,        // CLASS is IN.
+  0x02, 0x00,        // TTL (4 bytes) is 1 second.
+  0x00, 0x01,
+  0x00, 0x08,        // RDLENGTH is 8 bytes.
+  0x05, 'h', 'e', 'l', 'l', 'o',
+  0xc0, 0x0c
+};
+
+const uint8 kSamplePacketQuerySRV[] = {
+  // Header
+  0x00, 0x00,               // ID is zeroed out
+  0x00, 0x00,               // No flags.
+  0x00, 0x01,               // One question.
+  0x00, 0x00,               // 0 RRs (answers)
+  0x00, 0x00,               // 0 authority RRs
+  0x00, 0x00,               // 0 additional RRs
+
+  // Question
+  0x05, 'h', 'e', 'l', 'l', 'o',
+  0x07, '_', 'p', 'r', 'i', 'v', 'e', 't',
+  0x04, '_', 't', 'c', 'p',
+  0x05, 'l', 'o', 'c', 'a', 'l',
+  0x00,
+  0x00, 0x21,        // TYPE is SRV.
+  0x00, 0x01,        // CLASS is IN.
+};
+
+
+class MockServiceWatcherClient {
+ public:
+  MOCK_METHOD2(OnServiceUpdated,
+               void(ServiceWatcher::UpdateType, const std::string&));
+
+  ServiceWatcher::UpdatedCallback GetCallback() {
+    return base::Bind(&MockServiceWatcherClient::OnServiceUpdated,
+                      base::Unretained(this));
+  }
+};
+
+class ServiceDiscoveryTest : public ::testing::Test {
+ public:
+  ServiceDiscoveryTest()
+      : service_discovery_client_(&mdns_client_) {
+    mdns_client_.StartListening(&socket_factory_);
+  }
+
+  virtual ~ServiceDiscoveryTest() {
+  }
+
+ protected:
+  void RunFor(base::TimeDelta time_period) {
+    base::CancelableCallback<void()> callback(base::Bind(
+        &ServiceDiscoveryTest::Stop, base::Unretained(this)));
+    base::MessageLoop::current()->PostDelayedTask(
+        FROM_HERE, callback.callback(), time_period);
+
+    base::MessageLoop::current()->Run();
+    callback.Cancel();
+  }
+
+  void Stop() {
+    base::MessageLoop::current()->Quit();
+  }
+
+  net::MockMDnsSocketFactory socket_factory_;
+  net::MDnsClientImpl mdns_client_;
+  ServiceDiscoveryClientImpl service_discovery_client_;
+  base::MessageLoop loop_;
+};
+
+TEST_F(ServiceDiscoveryTest, AddRemoveService) {
+  StrictMock<MockServiceWatcherClient> delegate;
+
+  scoped_ptr<ServiceWatcher> watcher(
+      service_discovery_client_.CreateServiceWatcher(
+          "_privet._tcp.local", delegate.GetCallback()));
+
+  watcher->Start();
+
+  EXPECT_CALL(delegate, OnServiceUpdated(ServiceWatcher::UPDATE_ADDED,
+                                         "hello._privet._tcp.local"))
+      .Times(Exactly(1));
+
+  socket_factory_.SimulateReceive(kSamplePacketPTR, sizeof(kSamplePacketPTR));
+
+  EXPECT_CALL(delegate, OnServiceUpdated(ServiceWatcher::UPDATE_REMOVED,
+                                         "hello._privet._tcp.local"))
+      .Times(Exactly(1));
+
+  RunFor(base::TimeDelta::FromSeconds(2));
+};
+
+TEST_F(ServiceDiscoveryTest, DiscoverNewServices) {
+  StrictMock<MockServiceWatcherClient> delegate;
+
+  scoped_ptr<ServiceWatcher> watcher(
+      service_discovery_client_.CreateServiceWatcher(
+          "_privet._tcp.local", delegate.GetCallback()));
+
+  watcher->Start();
+
+  EXPECT_CALL(socket_factory_, OnSendTo(_)).Times(2);
+
+  watcher->DiscoverNewServices(false);
+
+  EXPECT_CALL(socket_factory_, OnSendTo(_)).Times(2);
+
+  RunFor(base::TimeDelta::FromSeconds(2));
+};
+
+TEST_F(ServiceDiscoveryTest, ReadCachedServices) {
+  socket_factory_.SimulateReceive(kSamplePacketPTR, sizeof(kSamplePacketPTR));
+
+  StrictMock<MockServiceWatcherClient> delegate;
+
+  scoped_ptr<ServiceWatcher> watcher(
+      service_discovery_client_.CreateServiceWatcher(
+          "_privet._tcp.local", delegate.GetCallback()));
+
+  watcher->Start();
+
+  EXPECT_CALL(delegate, OnServiceUpdated(ServiceWatcher::UPDATE_ADDED,
+                                         "hello._privet._tcp.local"))
+      .Times(Exactly(1));
+
+  base::MessageLoop::current()->RunUntilIdle();
+};
+
+
+TEST_F(ServiceDiscoveryTest, ReadCachedServicesMultiple) {
+  socket_factory_.SimulateReceive(kSamplePacketPTR2, sizeof(kSamplePacketPTR2));
+
+  StrictMock<MockServiceWatcherClient> delegate;
+  scoped_ptr<ServiceWatcher> watcher =
+      service_discovery_client_.CreateServiceWatcher(
+          "_privet._tcp.local", delegate.GetCallback());
+
+  watcher->Start();
+
+  EXPECT_CALL(delegate, OnServiceUpdated(ServiceWatcher::UPDATE_ADDED,
+                                         "hello._privet._tcp.local"))
+      .Times(Exactly(1));
+
+  EXPECT_CALL(delegate, OnServiceUpdated(ServiceWatcher::UPDATE_ADDED,
+                                         "gdbye._privet._tcp.local"))
+      .Times(Exactly(1));
+
+  base::MessageLoop::current()->RunUntilIdle();
+};
+
+
+TEST_F(ServiceDiscoveryTest, OnServiceChanged) {
+  StrictMock<MockServiceWatcherClient> delegate;
+  scoped_ptr<ServiceWatcher> watcher(
+      service_discovery_client_.CreateServiceWatcher(
+          "_privet._tcp.local", delegate.GetCallback()));
+
+  watcher->Start();
+
+  EXPECT_CALL(delegate, OnServiceUpdated(ServiceWatcher::UPDATE_ADDED,
+                                         "hello._privet._tcp.local"))
+      .Times(Exactly(1));
+
+  socket_factory_.SimulateReceive(kSamplePacketPTR, sizeof(kSamplePacketPTR));
+
+  base::MessageLoop::current()->RunUntilIdle();
+
+  EXPECT_CALL(delegate, OnServiceUpdated(ServiceWatcher::UPDATE_CHANGED,
+                                         "hello._privet._tcp.local"))
+      .Times(Exactly(1));
+
+  socket_factory_.SimulateReceive(kSamplePacketSRV, sizeof(kSamplePacketSRV));
+
+  socket_factory_.SimulateReceive(kSamplePacketTXT, sizeof(kSamplePacketTXT));
+
+  base::MessageLoop::current()->RunUntilIdle();
+};
+
+TEST_F(ServiceDiscoveryTest, SinglePacket) {
+  StrictMock<MockServiceWatcherClient> delegate;
+  scoped_ptr<ServiceWatcher> watcher(
+      service_discovery_client_.CreateServiceWatcher(
+          "_privet._tcp.local", delegate.GetCallback()));
+
+  watcher->Start();
+
+  EXPECT_CALL(delegate, OnServiceUpdated(ServiceWatcher::UPDATE_ADDED,
+                                         "hello._privet._tcp.local"))
+      .Times(Exactly(1));
+
+  socket_factory_.SimulateReceive(kSamplePacketPTR, sizeof(kSamplePacketPTR));
+
+  // Reset the "already updated" flag.
+  base::MessageLoop::current()->RunUntilIdle();
+
+  EXPECT_CALL(delegate, OnServiceUpdated(ServiceWatcher::UPDATE_CHANGED,
+                                         "hello._privet._tcp.local"))
+      .Times(Exactly(1));
+
+  socket_factory_.SimulateReceive(kSamplePacketSRV, sizeof(kSamplePacketSRV));
+
+  socket_factory_.SimulateReceive(kSamplePacketTXT, sizeof(kSamplePacketTXT));
+
+  base::MessageLoop::current()->RunUntilIdle();
+};
+
+TEST_F(ServiceDiscoveryTest, ActivelyRefreshServices) {
+  StrictMock<MockServiceWatcherClient> delegate;
+  scoped_ptr<ServiceWatcher> watcher(
+      service_discovery_client_.CreateServiceWatcher(
+          "_privet._tcp.local", delegate.GetCallback()));
+
+  watcher->Start();
+  watcher->SetActivelyRefreshServices(true);
+
+  EXPECT_CALL(delegate, OnServiceUpdated(ServiceWatcher::UPDATE_ADDED,
+                                         "hello._privet._tcp.local"))
+      .Times(Exactly(1));
+
+  std::string query_packet = std::string((const char*)(kSamplePacketQuerySRV),
+                                         sizeof(kSamplePacketQuerySRV));
+
+  EXPECT_CALL(socket_factory_, OnSendTo(query_packet))
+      .Times(2);
+
+  socket_factory_.SimulateReceive(kSamplePacketPTR, sizeof(kSamplePacketPTR));
+
+  base::MessageLoop::current()->RunUntilIdle();
+
+  socket_factory_.SimulateReceive(kSamplePacketSRV, sizeof(kSamplePacketSRV));
+
+  EXPECT_CALL(socket_factory_, OnSendTo(query_packet))
+      .Times(4);  // IPv4 and IPv6 at 85% and 95%
+
+  EXPECT_CALL(delegate, OnServiceUpdated(ServiceWatcher::UPDATE_REMOVED,
+                                         "hello._privet._tcp.local"))
+      .Times(Exactly(1));
+
+  RunFor(base::TimeDelta::FromSeconds(2));
+
+  base::MessageLoop::current()->RunUntilIdle();
+};
+
+
+class ServiceResolverTest : public ServiceDiscoveryTest {
+ public:
+  ServiceResolverTest() {
+    metadata_expected_.push_back("hello");
+    address_expected_ = net::HostPortPair("myhello.local", 8888);
+    ip_address_expected_.push_back(1);
+    ip_address_expected_.push_back(2);
+    ip_address_expected_.push_back(3);
+    ip_address_expected_.push_back(4);
+  }
+
+  ~ServiceResolverTest() {
+  }
+
+  void SetUp()  {
+    resolver_ = service_discovery_client_.CreateServiceResolver(
+                    "hello._privet._tcp.local",
+                     base::Bind(&ServiceResolverTest::OnFinishedResolving,
+                                base::Unretained(this)));
+  }
+
+  void OnFinishedResolving(ServiceResolver::RequestStatus request_status,
+                           const ServiceDescription& service_description) {
+    OnFinishedResolvingInternal(request_status,
+                                service_description.address.ToString(),
+                                service_description.metadata,
+                                service_description.ip_address);
+  }
+
+  MOCK_METHOD4(OnFinishedResolvingInternal,
+               void(ServiceResolver::RequestStatus,
+                    const std::string&,
+                    const std::vector<std::string>&,
+                    const net::IPAddressNumber&));
+
+ protected:
+  scoped_ptr<ServiceResolver> resolver_;
+  net::IPAddressNumber ip_address_;
+  net::HostPortPair address_expected_;
+  std::vector<std::string> metadata_expected_;
+  net::IPAddressNumber ip_address_expected_;
+};
+
+TEST_F(ServiceResolverTest, TxtAndSrvButNoA) {
+  EXPECT_CALL(socket_factory_, OnSendTo(_)).Times(4);
+
+  resolver_->StartResolving();
+
+  socket_factory_.SimulateReceive(kSamplePacketSRV, sizeof(kSamplePacketSRV));
+
+  base::MessageLoop::current()->RunUntilIdle();
+
+  EXPECT_CALL(*this,
+              OnFinishedResolvingInternal(ServiceResolver::STATUS_SUCCESS,
+                                          address_expected_.ToString(),
+                                          metadata_expected_,
+                                          net::IPAddressNumber()));
+
+  socket_factory_.SimulateReceive(kSamplePacketTXT, sizeof(kSamplePacketTXT));
+};
+
+TEST_F(ServiceResolverTest, TxtSrvAndA) {
+  EXPECT_CALL(socket_factory_, OnSendTo(_)).Times(4);
+
+  resolver_->StartResolving();
+
+  EXPECT_CALL(*this,
+              OnFinishedResolvingInternal(ServiceResolver::STATUS_SUCCESS,
+                                          address_expected_.ToString(),
+                                          metadata_expected_,
+                                          ip_address_expected_));
+
+  socket_factory_.SimulateReceive(kSamplePacketTXT, sizeof(kSamplePacketTXT));
+
+  socket_factory_.SimulateReceive(kSamplePacketSRVA, sizeof(kSamplePacketSRVA));
+};
+
+TEST_F(ServiceResolverTest, JustSrv) {
+  EXPECT_CALL(socket_factory_, OnSendTo(_)).Times(4);
+
+  resolver_->StartResolving();
+
+  EXPECT_CALL(*this,
+              OnFinishedResolvingInternal(ServiceResolver::STATUS_SUCCESS,
+                                          address_expected_.ToString(),
+                                          std::vector<std::string>(),
+                                          ip_address_expected_));
+
+  socket_factory_.SimulateReceive(kSamplePacketSRVA, sizeof(kSamplePacketSRVA));
+
+  // TODO(noamsml): When NSEC record support is added, change this to use an
+  // NSEC record.
+  RunFor(base::TimeDelta::FromSeconds(4));
+};
+
+TEST_F(ServiceResolverTest, WithNothing) {
+  EXPECT_CALL(socket_factory_, OnSendTo(_)).Times(4);
+
+  resolver_->StartResolving();
+
+  EXPECT_CALL(*this, OnFinishedResolvingInternal(
+                         ServiceResolver::STATUS_REQUEST_TIMEOUT, _, _, _));
+
+  // TODO(noamsml): When NSEC record support is added, change this to use an
+  // NSEC record.
+  RunFor(base::TimeDelta::FromSeconds(4));
+};
+
+}  // namespace
+
+}  // namespace local_discovery