Initial chrome.mdns API.

Currently just implements the API layer which allows adding a listener and defines a manifest key to specify mdns service types to watch.

BUG=280900
TBR=erg

Review URL: https://chromiumcodereview.appspot.com/23437015

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@221619 0039d316-1c4b-4281-b951-d872f2087c98

27 files changed, 591 insertions, 7 deletions

diff --git a/chrome/browser/extensions/api/mdns/OWNERS b/chrome/browser/extensions/api/mdns/OWNERS
new file mode 100644
index 0000000..cb84d70
--- /dev/null
+++ b/chrome/browser/extensions/api/mdns/OWNERS
@@ -0,0 +1,2 @@
+justinlin@chromium.org
+mfoltz@chromium.org
diff --git a/chrome/browser/extensions/api/mdns/dns_sd_registry.cc b/chrome/browser/extensions/api/mdns/dns_sd_registry.cc
new file mode 100644
index 0000000..ca9980b
--- /dev/null
+++ b/chrome/browser/extensions/api/mdns/dns_sd_registry.cc
@@ -0,0 +1,28 @@
+// Copyright 2013 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/browser/extensions/api/mdns/dns_sd_registry.h"
+
+namespace extensions {
+
+DnsSdRegistry::DnsSdRegistry() {}
+DnsSdRegistry::~DnsSdRegistry() {}
+
+void DnsSdRegistry::AddObserver(DnsSdObserver* observer) {
+  observers_.AddObserver(observer);
+}
+
+void DnsSdRegistry::RemoveObserver(DnsSdObserver* observer) {
+  observers_.RemoveObserver(observer);
+}
+
+void DnsSdRegistry::RegisterDnsSdListener(std::string service_type) {
+  // TODO(mfoltz): Start DNS-SD service.
+}
+
+void DnsSdRegistry::UnregisterDnsSdListener(std::string service_type) {
+  // TODO(mfoltz): Stop DNS-SD service.
+}
+
+}  // namespace extensions
diff --git a/chrome/browser/extensions/api/mdns/dns_sd_registry.h b/chrome/browser/extensions/api/mdns/dns_sd_registry.h
new file mode 100644
index 0000000..4deb759
--- /dev/null
+++ b/chrome/browser/extensions/api/mdns/dns_sd_registry.h
@@ -0,0 +1,47 @@
+// Copyright 2013 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_BROWSER_EXTENSIONS_API_MDNS_DNS_SD_REGISTRY_H_
+#define CHROME_BROWSER_EXTENSIONS_API_MDNS_DNS_SD_REGISTRY_H_
+
+#include <string>
+#include <vector>
+
+#include "base/observer_list.h"
+
+namespace extensions {
+
+// Network Service Discovery registry class for keeping track of discovered
+// network services.
+class DnsSdRegistry {
+ public:
+  typedef std::vector<std::string> DnsSdServiceList;
+
+  class DnsSdObserver {
+   public:
+    virtual void OnDnsSdEvent(const std::string& service_type,
+                              const DnsSdServiceList& services) = 0;
+
+   protected:
+    virtual ~DnsSdObserver() {}
+  };
+
+  explicit DnsSdRegistry();
+  virtual ~DnsSdRegistry();
+
+  // Observer registration for parties interested in discovery events.
+  virtual void AddObserver(DnsSdObserver* observer);
+  virtual void RemoveObserver(DnsSdObserver* observer);
+
+  // DNS-SD-related discovery functionality.
+  virtual void RegisterDnsSdListener(std::string service_type);
+  virtual void UnregisterDnsSdListener(std::string service_type);
+
+ protected:
+  ObserverList<DnsSdObserver> observers_;
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_API_MDNS_DNS_SD_REGISTRY_H_
diff --git a/chrome/browser/extensions/api/mdns/mdns_api.cc b/chrome/browser/extensions/api/mdns/mdns_api.cc
new file mode 100644
index 0000000..1f74d3a
--- /dev/null
+++ b/chrome/browser/extensions/api/mdns/mdns_api.cc
@@ -0,0 +1,154 @@
+// Copyright 2013 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/browser/extensions/api/mdns/mdns_api.h"
+
+#include <vector>
+
+#include "base/lazy_instance.h"
+#include "chrome/browser/extensions/extension_service.h"
+#include "chrome/browser/extensions/extension_system.h"
+#include "chrome/common/extensions/api/mdns.h"
+
+namespace extensions {
+
+namespace mdns = api::mdns;
+
+namespace {
+
+// Whitelisted mDNS service types.
+const char kCastServiceType[] = "_googlecast._tcp.local";
+const char kTestServiceType[] = "_testing._tcp.local";
+
+bool IsServiceTypeWhitelisted(const std::string& service_type) {
+  return service_type == kCastServiceType ||
+         service_type == kTestServiceType;
+}
+
+}  // namespace
+
+MDnsAPI::MDnsAPI(Profile* profile) : profile_(profile) {
+  DCHECK(profile_);
+  ExtensionSystem::Get(profile)->event_router()->RegisterObserver(
+      this, mdns::OnServiceList::kEventName);
+}
+
+MDnsAPI::~MDnsAPI() {
+  if (dns_sd_registry_.get()) {
+    dns_sd_registry_->RemoveObserver(this);
+  }
+}
+
+// static
+MDnsAPI* MDnsAPI::Get(Profile* profile) {
+  return ProfileKeyedAPIFactory<MDnsAPI>::GetForProfile(profile);
+}
+
+static base::LazyInstance<ProfileKeyedAPIFactory<MDnsAPI> > g_factory =
+    LAZY_INSTANCE_INITIALIZER;
+
+// static
+ProfileKeyedAPIFactory<MDnsAPI>* MDnsAPI::GetFactoryInstance() {
+  return &g_factory.Get();
+}
+
+void MDnsAPI::SetDnsSdRegistryForTesting(
+    scoped_ptr<DnsSdRegistry> dns_sd_registry) {
+  dns_sd_registry_ = dns_sd_registry.Pass();
+}
+
+DnsSdRegistry* MDnsAPI::dns_sd_registry() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  if (!dns_sd_registry_.get()) {
+    dns_sd_registry_.reset(new extensions::DnsSdRegistry());
+    dns_sd_registry_->AddObserver(this);
+  }
+  return dns_sd_registry_.get();
+}
+
+void MDnsAPI::OnListenerAdded(const EventListenerInfo& details) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  UpdateMDnsListeners(details);
+}
+
+void MDnsAPI::OnListenerRemoved(const EventListenerInfo& details) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  UpdateMDnsListeners(details);
+}
+
+void MDnsAPI::UpdateMDnsListeners(const EventListenerInfo& details) {
+  std::set<std::string> new_service_types;
+
+  // Check all listeners for service type filers.
+  const EventListenerMap::ListenerList& listeners =
+      extensions::ExtensionSystem::Get(profile_)->event_router()->
+          listeners().GetEventListenersByName(details.event_name);
+  for (EventListenerMap::ListenerList::const_iterator it = listeners.begin();
+       it != listeners.end(); ++it) {
+    base::DictionaryValue* filter = ((*it)->filter.get());
+    for (base::DictionaryValue::Iterator iter(*filter);
+       !iter.IsAtEnd(); iter.Advance()) {
+    }
+
+    std::string filter_value;
+    filter->GetStringASCII(kEventFilterServiceTypeKey, &filter_value);
+    if (filter_value.empty())
+      continue;
+
+    new_service_types.insert(filter_value);
+  }
+
+  // Find all the added and removed service types since last update.
+  std::set<std::string> added_service_types =
+      base::STLSetDifference<std::set<std::string> >(
+          service_types_, new_service_types);
+  std::set<std::string> removed_service_types =
+      base::STLSetDifference<std::set<std::string> >(
+          new_service_types, service_types_);
+
+  // Update the registry.
+  DnsSdRegistry* registry = dns_sd_registry();
+  for (std::set<std::string>::iterator it = added_service_types.begin();
+       it != added_service_types.end(); ++it) {
+    if (IsServiceTypeWhitelisted(*it))
+      registry->RegisterDnsSdListener(*it);
+  }
+  for (std::set<std::string>::iterator it = removed_service_types.begin();
+       it != removed_service_types.end(); ++it) {
+    if (IsServiceTypeWhitelisted(*it))
+      registry->UnregisterDnsSdListener(*it);
+  }
+
+  service_types_ = new_service_types;
+}
+
+void MDnsAPI::OnDnsSdEvent(const std::string& service_type,
+                           const DnsSdRegistry::DnsSdServiceList& services) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  if (services.size() == 0)
+    return;
+
+  std::vector<linked_ptr<mdns::MDnsService> > args;
+  for (DnsSdRegistry::DnsSdServiceList::const_iterator it = services.begin();
+       it != services.end(); ++it) {
+    linked_ptr<mdns::MDnsService> mdns_service =
+        make_linked_ptr(new mdns::MDnsService);
+    // TODO(justinlin, mfoltz): Copy data from service list.
+    mdns_service->service_name = service_type;
+    args.push_back(mdns_service);
+  }
+
+  scoped_ptr<base::ListValue> results = mdns::OnServiceList::Create(args);
+  scoped_ptr<Event> event(
+      new Event(mdns::OnServiceList::kEventName, results.Pass()));
+  event->restrict_to_profile = profile_;
+  event->filter_info.SetServiceType(service_type);
+
+  // TODO(justinlin): To avoid having listeners without filters getting all
+  // events, modify API to have this event require filters.
+  extensions::ExtensionSystem::Get(profile_)->event_router()->
+      BroadcastEvent(event.Pass());
+}
+
+}  // namespace extensions
diff --git a/chrome/browser/extensions/api/mdns/mdns_api.h b/chrome/browser/extensions/api/mdns/mdns_api.h
new file mode 100644
index 0000000..851e0b9
--- /dev/null
+++ b/chrome/browser/extensions/api/mdns/mdns_api.h
@@ -0,0 +1,80 @@
+// Copyright 2013 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_BROWSER_EXTENSIONS_API_MDNS_MDNS_API_H_
+#define CHROME_BROWSER_EXTENSIONS_API_MDNS_MDNS_API_H_
+
+#include <set>
+#include <string>
+
+#include "base/memory/scoped_ptr.h"
+#include "base/threading/thread_checker.h"
+#include "chrome/browser/extensions/api/mdns/dns_sd_registry.h"
+#include "chrome/browser/extensions/api/profile_keyed_api_factory.h"
+#include "chrome/browser/extensions/event_router.h"
+
+namespace extensions {
+
+class DnsSdRegistry;
+
+// MDnsAPI is instantiated with the profile and will listen for extensions that
+// register listeners for the chrome.mdns extension API. It will use a registry
+// class to start the mDNS listener process (if necessary) and observe new
+// service events to dispatch them to registered extensions.
+class MDnsAPI : public ProfileKeyedAPI,
+                public EventRouter::Observer,
+                public DnsSdRegistry::DnsSdObserver {
+ public:
+  explicit MDnsAPI(Profile* profile);
+  virtual ~MDnsAPI();
+
+  static MDnsAPI* Get(Profile* profile);
+
+  // ProfileKeyedAPI implementation.
+  static ProfileKeyedAPIFactory<MDnsAPI>* GetFactoryInstance();
+
+  // Used to mock out the DnsSdRegistry for testing.
+  void SetDnsSdRegistryForTesting(scoped_ptr<DnsSdRegistry> registry);
+
+ protected:
+  // Retrieve an instance of the registry. Lazily created when needed.
+  virtual DnsSdRegistry* dns_sd_registry();
+
+ private:
+  friend class ProfileKeyedAPIFactory<MDnsAPI>;
+
+  // EventRouter::Observer:
+  virtual void OnListenerAdded(const EventListenerInfo& details) OVERRIDE;
+  virtual void OnListenerRemoved(const EventListenerInfo& details) OVERRIDE;
+
+  // DnsSdRegistry::Observer
+  virtual void OnDnsSdEvent(
+      const std::string& service_type,
+      const DnsSdRegistry::DnsSdServiceList& services) OVERRIDE;
+
+  // ProfileKeyedAPI implementation.
+  static const char* service_name() {
+    return "MDnsAPI";
+  }
+
+  static const bool kServiceIsCreatedWithBrowserContext = true;
+  static const bool kServiceIsNULLWhileTesting = true;
+
+  // Update the current list of service types and update the registry.
+  void UpdateMDnsListeners(const EventListenerInfo& details);
+
+  // Ensure methods are only called on UI thread.
+  base::ThreadChecker thread_checker_;
+  Profile* const profile_;
+  // Lazily created on first access and destroyed with this API class.
+  scoped_ptr<DnsSdRegistry> dns_sd_registry_;
+  // Current set of service types registered with the registry.
+  std::set<std::string> service_types_;
+
+  DISALLOW_COPY_AND_ASSIGN(MDnsAPI);
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_API_MDNS_MDNS_API_H_
diff --git a/chrome/browser/extensions/api/mdns/mdns_apitest.cc b/chrome/browser/extensions/api/mdns/mdns_apitest.cc
new file mode 100644
index 0000000..46349dc
--- /dev/null
+++ b/chrome/browser/extensions/api/mdns/mdns_apitest.cc
@@ -0,0 +1,120 @@
+// Copyright 2013 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/command_line.h"
+#include "chrome/browser/extensions/api/mdns/mdns_api.h"
+#include "chrome/browser/extensions/extension_apitest.h"
+#include "chrome/browser/extensions/extension_service.h"
+#include "chrome/common/chrome_switches.h"
+#include "chrome/common/extensions/api/mdns.h"
+#include "testing/gmock/include/gmock/gmock.h"
+
+using extensions::DnsSdRegistry;
+using ::testing::A;
+using ::testing::_;
+
+namespace api = extensions::api;
+
+namespace {
+
+class MockDnsSdRegistry : public DnsSdRegistry {
+ public:
+  explicit MockDnsSdRegistry(extensions::MDnsAPI* api) : api_(api) {}
+  virtual ~MockDnsSdRegistry() {}
+
+  MOCK_METHOD1(AddObserver, void(DnsSdObserver* observer));
+  MOCK_METHOD1(RemoveObserver, void(DnsSdObserver* observer));
+  MOCK_METHOD1(RegisterDnsSdListener, void(std::string service_type));
+  MOCK_METHOD1(UnregisterDnsSdListener, void(std::string service_type));
+
+  void DispatchMDnsEvent(const std::string& service_type,
+                         const DnsSdServiceList& services) {
+    api_->OnDnsSdEvent(service_type, services);
+  }
+
+ private:
+  extensions::DnsSdRegistry::DnsSdObserver* api_;
+};
+
+class MDnsAPITest : public ExtensionApiTest {
+ public:
+  MDnsAPITest() {}
+
+  virtual void SetUpCommandLine(CommandLine* command_line) OVERRIDE {
+    ExtensionApiTest::SetUpCommandLine(command_line);
+    command_line->AppendSwitchASCII(
+        switches::kWhitelistedExtensionID, "ddchlicdkolnonkihahngkmmmjnjlkkf");
+  }
+
+  void SetUpTestDnsSdRegistry() {
+    extensions::MDnsAPI* api = extensions::MDnsAPI::Get(profile());
+    dns_sd_registry_ = new MockDnsSdRegistry(api);
+    // Transfers ownership of the registry instance.
+    api->SetDnsSdRegistryForTesting(
+        make_scoped_ptr<DnsSdRegistry>(dns_sd_registry_).Pass());
+  }
+
+ protected:
+  MockDnsSdRegistry* dns_sd_registry_;
+};
+
+}  // namespace
+
+// Test loading extension, registering an MDNS listener and dispatching events.
+IN_PROC_BROWSER_TEST_F(MDnsAPITest, RegisterListener) {
+  const std::string& service_type = "_googlecast._tcp.local";
+  SetUpTestDnsSdRegistry();
+
+  EXPECT_CALL(*dns_sd_registry_, RegisterDnsSdListener(service_type))
+      .Times(1);
+  EXPECT_CALL(*dns_sd_registry_, UnregisterDnsSdListener(service_type))
+      .Times(1);
+  EXPECT_CALL(*dns_sd_registry_,
+              RemoveObserver(A<extensions::DnsSdRegistry::DnsSdObserver*>()))
+      .Times(1);
+
+  EXPECT_TRUE(RunExtensionSubtest("mdns/api", "register_listener.html"))
+      << message_;
+
+  ResultCatcher catcher;
+  // Dispatch 3 events, one of which should not be sent to the test extension.
+  std::vector<std::string> services;
+  services.push_back("test");
+
+  dns_sd_registry_->DispatchMDnsEvent(service_type, services);
+  dns_sd_registry_->DispatchMDnsEvent("_uninteresting._tcp.local", services);
+  dns_sd_registry_->DispatchMDnsEvent(service_type, services);
+  EXPECT_TRUE(catcher.GetNextResult()) << catcher.message();
+}
+
+// Test loading extension and registering multiple listeners.
+IN_PROC_BROWSER_TEST_F(MDnsAPITest, RegisterMultipleListeners) {
+  const std::string& service_type = "_googlecast._tcp.local";
+  const std::string& test_service_type = "_testing._tcp.local";
+  SetUpTestDnsSdRegistry();
+
+  EXPECT_CALL(*dns_sd_registry_, RegisterDnsSdListener(service_type))
+      .Times(1);
+  EXPECT_CALL(*dns_sd_registry_, UnregisterDnsSdListener(service_type))
+      .Times(1);
+  EXPECT_CALL(*dns_sd_registry_, RegisterDnsSdListener(test_service_type))
+      .Times(1);
+  EXPECT_CALL(*dns_sd_registry_, UnregisterDnsSdListener(test_service_type))
+      .Times(1);
+  EXPECT_CALL(*dns_sd_registry_,
+              RemoveObserver(A<extensions::DnsSdRegistry::DnsSdObserver*>()))
+      .Times(1);
+
+  EXPECT_TRUE(RunExtensionSubtest("mdns/api",
+                                  "register_multiple_listeners.html"))
+      << message_;
+
+  ResultCatcher catcher;
+  std::vector<std::string> services;
+  services.push_back("test");
+
+  dns_sd_registry_->DispatchMDnsEvent(service_type, services);
+  dns_sd_registry_->DispatchMDnsEvent(test_service_type, services);
+  EXPECT_TRUE(catcher.GetNextResult()) << catcher.message();
+}
diff --git a/chrome/browser/profiles/chrome_browser_main_extra_parts_profiles.cc b/chrome/browser/profiles/chrome_browser_main_extra_parts_profiles.cc
index 4052d82..3e0db36 100644
--- a/chrome/browser/profiles/chrome_browser_main_extra_parts_profiles.cc
+++ b/chrome/browser/profiles/chrome_browser_main_extra_parts_profiles.cc
@@ -37,6 +37,7 @@
 #include "chrome/browser/extensions/api/input/input.h"
 #include "chrome/browser/extensions/api/location/location_manager.h"
 #include "chrome/browser/extensions/api/management/management_api.h"
+#include "chrome/browser/extensions/api/mdns/mdns_api.h"
 #include "chrome/browser/extensions/api/media_galleries_private/media_galleries_private_api.h"
 #include "chrome/browser/extensions/api/omnibox/omnibox_api.h"
 #include "chrome/browser/extensions/api/preference/chrome_direct_setting_api.h"
@@ -239,6 +240,7 @@ EnsureBrowserContextKeyedServiceFactoriesBuilt() {
 #endif
   extensions::LocationManager::GetFactoryInstance();
   extensions::ManagementAPI::GetFactoryInstance();
+  extensions::MDnsAPI::GetFactoryInstance();
   extensions::MediaGalleriesPrivateAPI::GetFactoryInstance();
 #if defined(OS_CHROMEOS)
   extensions::MediaPlayerAPI::GetFactoryInstance();
diff --git a/chrome/chrome_browser_extensions.gypi b/chrome/chrome_browser_extensions.gypi
index 777ae89..add7b1d 100644
--- a/chrome/chrome_browser_extensions.gypi
+++ b/chrome/chrome_browser_extensions.gypi
@@ -329,6 +329,10 @@
         'browser/extensions/api/messaging/native_message_port.h',
         'browser/extensions/api/metrics_private/metrics_private_api.cc',
         'browser/extensions/api/metrics_private/metrics_private_api.h',
+        'browser/extensions/api/mdns/dns_sd_registry.h',
+        'browser/extensions/api/mdns/dns_sd_registry.cc',
+        'browser/extensions/api/mdns/mdns_api.h',
+        'browser/extensions/api/mdns/mdns_api.cc',
         'browser/extensions/api/module/module.cc',
         'browser/extensions/api/module/module.h',
         'browser/extensions/api/music_manager_private/device_id.cc',
diff --git a/chrome/chrome_tests.gypi b/chrome/chrome_tests.gypi
index 1d970f1..d0aee2c 100644
--- a/chrome/chrome_tests.gypi
+++ b/chrome/chrome_tests.gypi
@@ -1344,6 +1344,7 @@
         'browser/extensions/api/management/management_api_browsertest.cc',
         'browser/extensions/api/management/management_apitest.cc',
         'browser/extensions/api/management/management_browsertest.cc',
+        'browser/extensions/api/mdns/mdns_apitest.cc',
         'browser/extensions/api/media_galleries/media_galleries_apitest.cc',
         'browser/extensions/api/media_galleries_private/media_galleries_private_apitest.cc',
         'browser/extensions/api/media_galleries_private/media_galleries_watch_apitest.cc',
diff --git a/chrome/common/extensions/api/_api_features.json b/chrome/common/extensions/api/_api_features.json
index 1123226..094a8d6 100644
--- a/chrome/common/extensions/api/_api_features.json
+++ b/chrome/common/extensions/api/_api_features.json
@@ -351,6 +351,10 @@
     "dependencies": ["permission:metricsPrivate"],
     "contexts": ["blessed_extension"]
   },
+  "mdns": {
+    "dependencies": ["permission:mdns"],
+    "contexts": ["blessed_extension"]
+  },
   "musicManagerPrivate": {
     "dependencies": ["permission:musicManagerPrivate"],
     "contexts": ["blessed_extension"]
diff --git a/chrome/common/extensions/api/_permission_features.json b/chrome/common/extensions/api/_permission_features.json
index 651bb5b..f2bec5f 100644
--- a/chrome/common/extensions/api/_permission_features.json
+++ b/chrome/common/extensions/api/_permission_features.json
@@ -428,6 +428,18 @@
       "eemlkeanncmjljgehlbplemhmdmalhdc"   // CCD Release
     ]
   },
+  "mdns": {
+    "channel": "stable",
+    "extension_types": ["extension"],
+    "whitelist": [
+      "enhhojjnijigcajfphajepfemndkmdlo",  // Dev
+      "pkedcjkdefgpdelpbcmbmeomcjbeemfm",  // Trusted Tester
+      "fmfcbgogabcbclcofgocippekhfcmgfj",  // Staging
+      "hfaagokkkhdbgiakmmlclaapfelnkoah",  // Canary
+      "F155646B5D1CA545F7E1E4E20D573DFDD44C2540",  // Trusted Tester (public)
+      "16CA7A47AAE4BE49B1E75A6B960C3875E945B264"   // Release
+    ]
+  },
   "musicManagerPrivate": {
     "channel": "stable",
     "extension_types": ["platform_app"],
diff --git a/chrome/common/extensions/api/api.gyp b/chrome/common/extensions/api/api.gyp
index 211d594..aef722a 100644
--- a/chrome/common/extensions/api/api.gyp
+++ b/chrome/common/extensions/api/api.gyp
@@ -72,6 +72,7 @@
           'log_private.idl',
           'management.json',
           'manifest_types.json',
+          'mdns.idl',
           'media_galleries.idl',
           'media_galleries_private.idl',
           'media_player_private.json',
diff --git a/chrome/common/extensions/api/mdns.idl b/chrome/common/extensions/api/mdns.idl
new file mode 100644
index 0000000..b792327
--- /dev/null
+++ b/chrome/common/extensions/api/mdns.idl
@@ -0,0 +1,34 @@
+// Copyright 2013 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.
+
+// Use the <code>chrome.mdns</code> API to discover services over mDNS.
+// This comprises a subset of the features of the NSD spec:
+// http://www.w3.org/TR/discovery-api/
+namespace mdns {
+
+  // Represents a mDNS/DNS-SD service.
+  dictionary MDnsService {
+    // The service name of an mDNS advertised service,
+    // <instance_name>.<service_type>.
+    DOMString serviceName;
+
+    // The host:port pair of an mDNS advertised service.
+    DOMString serviceHostPort;
+
+    // The IP address of an mDNS advertised service.
+    DOMString ipAddress;
+
+    // Metadata for an mDNS advertised service.
+    DOMString[] serviceData;
+  };
+
+  interface Events {
+    // Event fired to inform clients of the current complete set of known
+    // available services. Clients should only need to store the list from the
+    // most recent event. The service types that the extension is interested in
+    // discovering should be declared as an array in the extensions manifest
+    // file with the 'mdns_service_types' key.
+    [supportsFilters=true] static void onServiceList(MDnsService[] services);
+  };
+};
diff --git a/chrome/common/extensions/permissions/api_permission.h b/chrome/common/extensions/permissions/api_permission.h
index 2b02412..ab50889 100644
--- a/chrome/common/extensions/permissions/api_permission.h
+++ b/chrome/common/extensions/permissions/api_permission.h
@@ -100,6 +100,7 @@ class APIPermission {
     kMediaGalleriesPrivate,
     kMediaPlayerPrivate,
     kMetricsPrivate,
+    kMDns,
     kMusicManagerPrivate,
     kNativeMessaging,
     kNetworkingPrivate,
diff --git a/chrome/common/extensions/permissions/chrome_api_permissions.cc b/chrome/common/extensions/permissions/chrome_api_permissions.cc
index 16b4d73..0f85128 100644
--- a/chrome/common/extensions/permissions/chrome_api_permissions.cc
+++ b/chrome/common/extensions/permissions/chrome_api_permissions.cc
@@ -187,6 +187,7 @@ std::vector<APIPermissionInfo*> ChromeAPIPermissions::GetAllPermissions()
       APIPermissionInfo::kFlagCannotBeOptional },
     { APIPermission::kMetricsPrivate, "metricsPrivate",
       APIPermissionInfo::kFlagCannotBeOptional },
+    { APIPermission::kMDns, "mdns", APIPermissionInfo::kFlagCannotBeOptional },
     { APIPermission::kMusicManagerPrivate, "musicManagerPrivate",
       APIPermissionInfo::kFlagCannotBeOptional,
       IDS_EXTENSION_PROMPT_WARNING_MUSIC_MANAGER_PRIVATE,
diff --git a/chrome/common/extensions/permissions/permission_set_unittest.cc b/chrome/common/extensions/permissions/permission_set_unittest.cc
index 4e37958..a96e873 100644
--- a/chrome/common/extensions/permissions/permission_set_unittest.cc
+++ b/chrome/common/extensions/permissions/permission_set_unittest.cc
@@ -716,6 +716,7 @@ TEST(PermissionsTest, PermissionMessages) {
   skip.insert(APIPermission::kMediaGalleriesPrivate);
   skip.insert(APIPermission::kMediaPlayerPrivate);
   skip.insert(APIPermission::kMetricsPrivate);
+  skip.insert(APIPermission::kMDns);
   skip.insert(APIPermission::kPreferencesPrivate);
   skip.insert(APIPermission::kRecoveryPrivate);
   skip.insert(APIPermission::kRtcPrivate);
diff --git a/chrome/renderer/extensions/event_bindings.cc b/chrome/renderer/extensions/event_bindings.cc
index 30cafb0..719187e 100644
--- a/chrome/renderer/extensions/event_bindings.cc
+++ b/chrome/renderer/extensions/event_bindings.cc
@@ -4,6 +4,9 @@
 
 #include "chrome/renderer/extensions/event_bindings.h"
 
+#include <map>
+#include <set>
+#include <string>
 #include <vector>
 
 #include "base/basictypes.h"
@@ -21,7 +24,6 @@
 #include "chrome/renderer/extensions/chrome_v8_context_set.h"
 #include "chrome/renderer/extensions/chrome_v8_extension.h"
 #include "chrome/renderer/extensions/dispatcher.h"
-#include "chrome/renderer/extensions/event_bindings.h"
 #include "chrome/renderer/extensions/extension_helper.h"
 #include "chrome/renderer/extensions/user_script_slave.h"
 #include "content/public/renderer/render_thread.h"
@@ -293,6 +295,11 @@ class ExtensionImpl : public ChromeV8Extension {
       v8::Handle<v8::Value> instance_id_value(object->Get(instance_id));
       info.SetInstanceID(instance_id_value->IntegerValue());
     }
+    v8::Handle<v8::String> service_type(v8::String::New("serviceType"));
+    if (object->Has(service_type)) {
+      v8::Handle<v8::Value> service_type_value(object->Get(service_type));
+      info.SetServiceType(*v8::String::AsciiValue(service_type_value));
+    }
     return info;
   }
 
diff --git a/chrome/renderer/resources/extensions/event.js b/chrome/renderer/resources/extensions/event.js
index 13ad277..c6c5a0f 100644
--- a/chrome/renderer/resources/extensions/event.js
+++ b/chrome/renderer/resources/extensions/event.js
@@ -228,7 +228,7 @@
   // Dispatches a named event with the given argument array. The args array is
   // the list of arguments that will be sent to the event callback.
   function dispatchEvent(name, args, filteringInfo) {
-    var listenerIDs = null;
+    var listenerIDs = [];
 
     if (filteringInfo)
       listenerIDs = eventNatives.MatchAgainstEventFilter(name, filteringInfo);
@@ -262,7 +262,11 @@
       if (!this.eventOptions_.supportsFilters)
         throw new Error("This event does not support filters.");
       if (filters.url && !(filters.url instanceof Array))
-        throw new Error("filters.url should be an array");
+        throw new Error("filters.url should be an array.");
+      if (filters.serviceType &&
+          !(typeof filters.serviceType === 'string')) {
+        throw new Error("filters.serviceType should be a string.")
+      }
     }
     var listener = {callback: cb, filters: filters};
     this.attach_(listener);
diff --git a/chrome/test/data/extensions/api_test/mdns/api/manifest.json b/chrome/test/data/extensions/api_test/mdns/api/manifest.json
new file mode 100644
index 0000000..96cfbed
--- /dev/null
+++ b/chrome/test/data/extensions/api_test/mdns/api/manifest.json
@@ -0,0 +1,8 @@
+ {
+  "key": "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQC8xv6iO+j4kzj1HiBL93+XVJH/CRyAQMUHS/Z0l8nCAzaAFkW/JsNwxJqQhrZspnxLqbQxNncXs6g6bsXAwKHiEs+LSs+bIv0Gc/2ycZdhXJ8GhEsSMakog5dpQd1681c2gLK/8CrAoewE/0GIKhaFcp7a2iZlGh4Am6fgMKy0iQIDAQAB",
+  "manifest_version": 2,
+  "name": "MDNS Extension",
+  "version": "1.0",
+  "description": "Test MDNS Extension",
+  "permissions": ["mdns"]
+}
diff --git a/chrome/test/data/extensions/api_test/mdns/api/register_listener.html b/chrome/test/data/extensions/api_test/mdns/api/register_listener.html
new file mode 100644
index 0000000..9b54ce5
--- /dev/null
+++ b/chrome/test/data/extensions/api_test/mdns/api/register_listener.html
@@ -0,0 +1 @@
+<script src="register_listener.js"></script>
diff --git a/chrome/test/data/extensions/api_test/mdns/api/register_listener.js b/chrome/test/data/extensions/api_test/mdns/api/register_listener.js
new file mode 100644
index 0000000..802a3ad
--- /dev/null
+++ b/chrome/test/data/extensions/api_test/mdns/api/register_listener.js
@@ -0,0 +1,22 @@
+// Copyright 2013 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.
+
+onload = function() {
+  chrome.test.runTests([
+    function registerListener() {
+      var numEvents = 0;
+      chrome.mdns.onServiceList.addListener(function(services) {
+        if (services[0].serviceName != '_googlecast._tcp.local') {
+          chrome.test.fail();
+          return;
+        } else if (numEvents == 1) {
+          chrome.test.succeed();
+        } else {
+          numEvents++;
+        }
+      }, {'serviceType': '_googlecast._tcp.local'});
+      chrome.test.notifyPass();
+    }
+  ]);
+};
diff --git a/chrome/test/data/extensions/api_test/mdns/api/register_multiple_listeners.html b/chrome/test/data/extensions/api_test/mdns/api/register_multiple_listeners.html
new file mode 100644
index 0000000..7490ea5
--- /dev/null
+++ b/chrome/test/data/extensions/api_test/mdns/api/register_multiple_listeners.html
@@ -0,0 +1 @@
+<script src="register_multiple_listeners.js"></script>
diff --git a/chrome/test/data/extensions/api_test/mdns/api/register_multiple_listeners.js b/chrome/test/data/extensions/api_test/mdns/api/register_multiple_listeners.js
new file mode 100644
index 0000000..0782153
--- /dev/null
+++ b/chrome/test/data/extensions/api_test/mdns/api/register_multiple_listeners.js
@@ -0,0 +1,23 @@
+// Copyright 2013 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.
+
+onload = function() {
+  chrome.test.runTests([
+    function registerListeners() {
+      var numEvents = 0;
+      chrome.mdns.onServiceList.addListener(function(services) {
+        if (numEvents++ == 1) {
+          chrome.test.succeed();
+        }
+      }, {'serviceType': '_googlecast._tcp.local'});
+
+      chrome.mdns.onServiceList.addListener(function(services) {
+        if (numEvents++ == 1) {
+          chrome.test.succeed();
+        }
+      }, {'serviceType': '_testing._tcp.local'});
+      chrome.test.notifyPass();
+    }
+  ]);
+};
diff --git a/extensions/common/event_filtering_info.cc b/extensions/common/event_filtering_info.cc
index 29566e8..cc46f96 100644
--- a/extensions/common/event_filtering_info.cc
+++ b/extensions/common/event_filtering_info.cc
@@ -38,11 +38,15 @@ scoped_ptr<base::Value> EventFilteringInfo::AsValue() const {
 
   if (has_instance_id_)
     result->SetInteger("instanceId", instance_id_);
+
+  if (!service_type_.empty())
+    result->SetString("serviceType", service_type_);
+
   return result.PassAs<base::Value>();
 }
 
 bool EventFilteringInfo::IsEmpty() const {
-  return !has_url_;
+  return !has_url_ && service_type_.empty();
 }
 
 }  // namespace extensions
diff --git a/extensions/common/event_filtering_info.h b/extensions/common/event_filtering_info.h
index 86309ab..a358798 100644
--- a/extensions/common/event_filtering_info.h
+++ b/extensions/common/event_filtering_info.h
@@ -28,6 +28,9 @@ class EventFilteringInfo {
   ~EventFilteringInfo();
   void SetURL(const GURL& url);
   void SetInstanceID(int instance_id);
+  void SetServiceType(const std::string& service_type) {
+    service_type_ = service_type;
+  }
 
   bool has_url() const { return has_url_; }
   const GURL& url() const { return url_; }
@@ -35,12 +38,16 @@ class EventFilteringInfo {
   bool has_instance_id() const { return has_instance_id_; }
   int instance_id() const { return instance_id_; }
 
+  bool has_service_type() const { return !service_type_.empty(); }
+  const std::string& service_type() const { return service_type_; }
+
   scoped_ptr<base::Value> AsValue() const;
   bool IsEmpty() const;
 
  private:
   bool has_url_;
   GURL url_;
+  std::string service_type_;
 
   bool has_instance_id_;
   int instance_id_;
diff --git a/extensions/common/event_matcher.cc b/extensions/common/event_matcher.cc
index ad76c89..8ae022a 100644
--- a/extensions/common/event_matcher.cc
+++ b/extensions/common/event_matcher.cc
@@ -12,6 +12,8 @@ const char kUrlFiltersKey[] = "url";
 
 namespace extensions {
 
+const char kEventFilterServiceTypeKey[] = "serviceType";
+
 EventMatcher::EventMatcher(scoped_ptr<base::DictionaryValue> filter,
                            int routing_id)
     : filter_(filter.Pass()),
@@ -23,10 +25,13 @@ EventMatcher::~EventMatcher() {
 
 bool EventMatcher::MatchNonURLCriteria(
     const EventFilteringInfo& event_info) const {
-  if (!event_info.has_instance_id())
-    return true;
+  if (event_info.has_instance_id()) {
+    return event_info.instance_id() == GetInstanceID();
+  }
 
-  return event_info.instance_id() == GetInstanceID();
+  const std::string& service_type_filter = GetServiceTypeFilter();
+  return service_type_filter.empty() ||
+         service_type_filter == event_info.service_type();
 }
 
 int EventMatcher::GetURLFilterCount() const {
@@ -48,6 +53,12 @@ int EventMatcher::HasURLFilters() const {
   return GetURLFilterCount() != 0;
 }
 
+std::string EventMatcher::GetServiceTypeFilter() const {
+  std::string service_type_filter;
+  filter_->GetStringASCII(kEventFilterServiceTypeKey, &service_type_filter);
+  return service_type_filter;
+}
+
 int EventMatcher::GetInstanceID() const {
   int instance_id = 0;
   filter_->GetInteger("instanceId", &instance_id);
diff --git a/extensions/common/event_matcher.h b/extensions/common/event_matcher.h
index 7843fce..bd0ce7b 100644
--- a/extensions/common/event_matcher.h
+++ b/extensions/common/event_matcher.h
@@ -12,6 +12,8 @@ namespace extensions {
 
 class EventFilteringInfo;
 
+extern const char kEventFilterServiceTypeKey[];
+
 // Matches EventFilteringInfos against a set of criteria. This is intended to
 // be used by EventFilter which performs efficient URL matching across
 // potentially many EventMatchers itself. This is why this class only exposes
@@ -29,6 +31,8 @@ class EventMatcher {
   int GetURLFilterCount() const;
   bool GetURLFilter(int i, base::DictionaryValue** url_filter_out);
 
+  std::string GetServiceTypeFilter() const;
+
   int HasURLFilters() const;
 
   int GetInstanceID() const;