Offline state detection for linux, using new D-Bus library.

BUG=53473
TEST=see attachment on bug 7469

Review URL: http://codereview.chromium.org/8249008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@110344 0039d316-1c4b-4281-b951-d872f2087c98

7 files changed, 487 insertions, 12 deletions

diff --git a/net/DEPS b/net/DEPS
index c198216..52142e6 100644
--- a/net/DEPS
+++ b/net/DEPS
@@ -1,5 +1,6 @@
 include_rules = [
   "+crypto",
+  "+dbus",
   "+jni",
   "+third_party/apple_apsl",
   "+third_party/libevent",
diff --git a/net/base/network_change_notifier.cc b/net/base/network_change_notifier.cc
index 00e6f0d..ea4f96c 100644
--- a/net/base/network_change_notifier.cc
+++ b/net/base/network_change_notifier.cc
@@ -60,7 +60,7 @@ NetworkChangeNotifier* NetworkChangeNotifier::Create() {
   CHECK(false);
   return NULL;
 #elif defined(OS_LINUX) || defined(OS_ANDROID)
-  return new NetworkChangeNotifierLinux();
+  return NetworkChangeNotifierLinux::Create();
 #elif defined(OS_MACOSX)
   return new NetworkChangeNotifierMac();
 #else
diff --git a/net/base/network_change_notifier.h b/net/base/network_change_notifier.h
index 85fff2c9..94e23a9 100644
--- a/net/base/network_change_notifier.h
+++ b/net/base/network_change_notifier.h
@@ -136,6 +136,7 @@ class NET_EXPORT NetworkChangeNotifier {
   static void NotifyObserversOfDNSChange();
 
  private:
+  friend class NetworkChangeNotifierLinuxTest;
   friend class NetworkChangeNotifierWinTest;
 
   // Allows a second NetworkChangeNotifier to be created for unit testing, so
diff --git a/net/base/network_change_notifier_linux.cc b/net/base/network_change_notifier_linux.cc
index 1e6db14..95f54e2 100644
--- a/net/base/network_change_notifier_linux.cc
+++ b/net/base/network_change_notifier_linux.cc
@@ -1,6 +1,11 @@
 // Copyright (c) 2011 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.
+//
+// This implementation of NetworkChangeNotifier's offline state detection
+// depends on D-Bus and NetworkManager, and is known to work on at least
+// GNOME version 2.30.  If D-Bus or NetworkManager are unavailable, this
+// implementation will always behave as if it is online.
 
 #include "net/base/network_change_notifier_linux.h"
 
@@ -15,7 +20,13 @@
 #include "base/file_util.h"
 #include "base/files/file_path_watcher.h"
 #include "base/memory/weak_ptr.h"
+#include "base/synchronization/lock.h"
+#include "base/synchronization/waitable_event.h"
+#include "base/threading/platform_thread.h"
 #include "base/threading/thread.h"
+#include "dbus/bus.h"
+#include "dbus/message.h"
+#include "dbus/object_proxy.h"
 #include "net/base/net_errors.h"
 #include "net/base/network_change_notifier_netlink_linux.h"
 
@@ -27,6 +38,190 @@ namespace {
 
 const int kInvalidSocket = -1;
 
+const char kNetworkManagerServiceName[] = "org.freedesktop.NetworkManager";
+const char kNetworkManagerPath[] = "/org/freedesktop/NetworkManager";
+const char kNetworkManagerInterface[] = "org.freedesktop.NetworkManager";
+
+// http://projects.gnome.org/NetworkManager/developers/spec-08.html#type-NM_STATE
+enum {
+  NM_LEGACY_STATE_UNKNOWN = 0,
+  NM_LEGACY_STATE_ASLEEP = 1,
+  NM_LEGACY_STATE_CONNECTING = 2,
+  NM_LEGACY_STATE_CONNECTED = 3,
+  NM_LEGACY_STATE_DISCONNECTED = 4
+};
+
+// http://projects.gnome.org/NetworkManager/developers/migrating-to-09/spec.html#type-NM_STATE
+enum {
+  NM_STATE_UNKNOWN = 0,
+  NM_STATE_ASLEEP = 10,
+  NM_STATE_DISCONNECTED = 20,
+  NM_STATE_DISCONNECTING = 30,
+  NM_STATE_CONNECTING = 40,
+  NM_STATE_CONNECTED_LOCAL = 50,
+  NM_STATE_CONNECTED_SITE = 60,
+  NM_STATE_CONNECTED_GLOBAL = 70
+};
+
+// A wrapper around NetworkManager's D-Bus API.
+class NetworkManagerApi {
+ public:
+  NetworkManagerApi(const base::Closure& notification_callback, dbus::Bus* bus)
+      : is_offline_(false),
+        offline_state_initialized_(true /*manual_reset*/, false),
+        notification_callback_(notification_callback),
+        helper_thread_id_(base::kInvalidThreadId),
+        ALLOW_THIS_IN_INITIALIZER_LIST(ptr_factory_(this)),
+        system_bus_(bus) { }
+
+  ~NetworkManagerApi() { }
+
+  // Should be called on a helper thread which must be of type IO.
+  void Init();
+
+  // Must be called by the helper thread's CleanUp() method.
+  void CleanUp();
+
+  // Implementation of NetworkChangeNotifierLinux::IsCurrentlyOffline().
+  // Safe to call from any thread, but will block until Init() has completed.
+  bool IsCurrentlyOffline();
+
+ private:
+  // Callbacks for D-Bus API.
+  void OnStateChanged(dbus::Message* message);
+
+  void OnResponse(dbus::Response* response) {
+    OnStateChanged(response);
+    offline_state_initialized_.Signal();
+  }
+
+  void OnSignaled(dbus::Signal* signal) {
+    OnStateChanged(signal);
+  }
+
+  void OnConnected(const std::string&, const std::string&, bool success) {
+    if (!success) {
+      DLOG(WARNING) << "Failed to set up offline state detection";
+      offline_state_initialized_.Signal();
+    }
+  }
+
+  // Converts a NetworkManager state uint to a bool.
+  static bool StateIsOffline(uint32 state);
+
+  bool is_offline_;
+  base::Lock is_offline_lock_;
+  base::WaitableEvent offline_state_initialized_;
+
+  base::Closure notification_callback_;
+
+  base::PlatformThreadId helper_thread_id_;
+
+  base::WeakPtrFactory<NetworkManagerApi> ptr_factory_;
+
+  scoped_refptr<dbus::Bus> system_bus_;
+
+  DISALLOW_COPY_AND_ASSIGN(NetworkManagerApi);
+};
+
+void NetworkManagerApi::Init() {
+  // D-Bus requires an IO MessageLoop.
+  DCHECK_EQ(MessageLoop::current()->type(), MessageLoop::TYPE_IO);
+  helper_thread_id_ = base::PlatformThread::CurrentId();
+
+  if (!system_bus_) {
+    dbus::Bus::Options options;
+    options.bus_type = dbus::Bus::SYSTEM;
+    options.connection_type = dbus::Bus::PRIVATE;
+    system_bus_ = new dbus::Bus(options);
+  }
+
+  dbus::ObjectProxy* proxy =
+      system_bus_->GetObjectProxy(kNetworkManagerServiceName,
+                                  kNetworkManagerPath);
+
+  // Get the initial state asynchronously.
+  dbus::MethodCall method_call(DBUS_INTERFACE_PROPERTIES, "Get");
+  dbus::MessageWriter builder(&method_call);
+  builder.AppendString(kNetworkManagerInterface);
+  builder.AppendString("State");
+  proxy->CallMethod(
+      &method_call, dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
+      base::Bind(&NetworkManagerApi::OnResponse, ptr_factory_.GetWeakPtr()));
+
+  // And sign up for notifications.
+  proxy->ConnectToSignal(
+      kNetworkManagerInterface,
+      "StateChanged",
+      base::Bind(&NetworkManagerApi::OnSignaled, ptr_factory_.GetWeakPtr()),
+      base::Bind(&NetworkManagerApi::OnConnected, ptr_factory_.GetWeakPtr()));
+}
+
+void NetworkManagerApi::CleanUp() {
+  DCHECK_EQ(helper_thread_id_, base::PlatformThread::CurrentId());
+  ptr_factory_.InvalidateWeakPtrs();
+}
+
+void NetworkManagerApi::OnStateChanged(dbus::Message* message) {
+  DCHECK_EQ(helper_thread_id_, base::PlatformThread::CurrentId());
+  if (!message) {
+    DLOG(WARNING) << "No response received for initial state request";
+    return;
+  }
+  dbus::MessageReader reader(message);
+  uint32 state = 0;
+  if (!reader.HasMoreData() || !reader.PopUint32(&state)) {
+    DLOG(WARNING) << "Unexpected response for NetworkManager State request: "
+                  << message->ToString();
+    return;
+  }
+  bool new_is_offline = StateIsOffline(state);
+  {
+    base::AutoLock lock(is_offline_lock_);
+    if (is_offline_ != new_is_offline)
+      is_offline_ = new_is_offline;
+    else
+      return;
+  }
+  if (offline_state_initialized_.IsSignaled())
+    notification_callback_.Run();
+}
+
+bool NetworkManagerApi::StateIsOffline(uint32 state) {
+  switch (state) {
+    case NM_LEGACY_STATE_CONNECTED:
+    case NM_STATE_CONNECTED_SITE:
+    case NM_STATE_CONNECTED_GLOBAL:
+      // Definitely connected
+      return false;
+    case NM_LEGACY_STATE_DISCONNECTED:
+    case NM_STATE_DISCONNECTED:
+      // Definitely disconnected
+      return true;
+    case NM_STATE_CONNECTED_LOCAL:
+      // Local networking only; I'm treating this as offline (keybuk)
+      return true;
+    case NM_LEGACY_STATE_CONNECTING:
+    case NM_STATE_DISCONNECTING:
+    case NM_STATE_CONNECTING:
+      // In-flight change to connection status currently underway
+      return true;
+    case NM_LEGACY_STATE_ASLEEP:
+    case NM_STATE_ASLEEP:
+      // Networking disabled or no devices on system
+      return true;
+    default:
+      // Unknown status
+      return false;
+  }
+}
+
+bool NetworkManagerApi::IsCurrentlyOffline() {
+  offline_state_initialized_.Wait();
+  base::AutoLock lock(is_offline_lock_);
+  return is_offline_;
+}
+
 class DNSWatchDelegate : public FilePathWatcher::Delegate {
  public:
   explicit DNSWatchDelegate(const base::Closure& callback)
@@ -54,13 +249,19 @@ void DNSWatchDelegate::OnFilePathError(const FilePath& path) {
 class NetworkChangeNotifierLinux::Thread
     : public base::Thread, public MessageLoopForIO::Watcher {
  public:
-  Thread();
+  explicit Thread(dbus::Bus* bus);
   virtual ~Thread();
 
   // MessageLoopForIO::Watcher:
   virtual void OnFileCanReadWithoutBlocking(int fd);
   virtual void OnFileCanWriteWithoutBlocking(int /* fd */);
 
+  // Plumbing for NetworkChangeNotifier::IsCurrentlyOffline.
+  // Safe to call from any thread.
+  bool IsCurrentlyOffline() {
+    return network_manager_api_.IsCurrentlyOffline();
+  }
+
  protected:
   // base::Thread
   virtual void Init();
@@ -71,10 +272,14 @@ class NetworkChangeNotifierLinux::Thread
     NetworkChangeNotifier::NotifyObserversOfIPAddressChange();
   }
 
-  void NotifyObserversOfDNSChange() {
+  static void NotifyObserversOfDNSChange() {
     NetworkChangeNotifier::NotifyObserversOfDNSChange();
   }
 
+  static void NotifyObserversOfOnlineStateChange() {
+    NetworkChangeNotifier::NotifyObserversOfOnlineStateChange();
+  }
+
   // Starts listening for netlink messages.  Also handles the messages if there
   // are any available on the netlink socket.
   void ListenForNotifications();
@@ -96,13 +301,20 @@ class NetworkChangeNotifierLinux::Thread
   scoped_ptr<base::files::FilePathWatcher> hosts_file_watcher_;
   scoped_refptr<DNSWatchDelegate> file_watcher_delegate_;
 
+  // Used to detect online/offline state changes.
+  NetworkManagerApi network_manager_api_;
+
   DISALLOW_COPY_AND_ASSIGN(Thread);
 };
 
-NetworkChangeNotifierLinux::Thread::Thread()
+NetworkChangeNotifierLinux::Thread::Thread(dbus::Bus* bus)
     : base::Thread("NetworkChangeNotifier"),
       netlink_fd_(kInvalidSocket),
-      ALLOW_THIS_IN_INITIALIZER_LIST(ptr_factory_(this)) {
+      ALLOW_THIS_IN_INITIALIZER_LIST(ptr_factory_(this)),
+      network_manager_api_(
+          base::Bind(&NetworkChangeNotifierLinux::Thread
+                     ::NotifyObserversOfOnlineStateChange),
+          bus) {
 }
 
 NetworkChangeNotifierLinux::Thread::~Thread() {
@@ -113,8 +325,7 @@ void NetworkChangeNotifierLinux::Thread::Init() {
   resolv_file_watcher_.reset(new FilePathWatcher);
   hosts_file_watcher_.reset(new FilePathWatcher);
   file_watcher_delegate_ = new DNSWatchDelegate(base::Bind(
-      &NetworkChangeNotifierLinux::Thread::NotifyObserversOfDNSChange,
-      base::Unretained(this)));
+      &NetworkChangeNotifierLinux::Thread::NotifyObserversOfDNSChange));
   if (!resolv_file_watcher_->Watch(
           FilePath(FILE_PATH_LITERAL("/etc/resolv.conf")),
           file_watcher_delegate_.get())) {
@@ -130,6 +341,8 @@ void NetworkChangeNotifierLinux::Thread::Init() {
     return;
   }
   ListenForNotifications();
+
+  network_manager_api_.Init();
 }
 
 void NetworkChangeNotifierLinux::Thread::CleanUp() {
@@ -143,6 +356,8 @@ void NetworkChangeNotifierLinux::Thread::CleanUp() {
   // into us via the delegate during destruction.
   resolv_file_watcher_.reset();
   hosts_file_watcher_.reset();
+
+  network_manager_api_.CleanUp();
 }
 
 void NetworkChangeNotifierLinux::Thread::OnFileCanReadWithoutBlocking(int fd) {
@@ -206,8 +421,17 @@ int NetworkChangeNotifierLinux::Thread::ReadNotificationMessage(
   return ERR_IO_PENDING;
 }
 
-NetworkChangeNotifierLinux::NetworkChangeNotifierLinux()
-    : notifier_thread_(new Thread) {
+NetworkChangeNotifierLinux* NetworkChangeNotifierLinux::Create() {
+  return new NetworkChangeNotifierLinux(NULL);
+}
+
+NetworkChangeNotifierLinux* NetworkChangeNotifierLinux::CreateForTest(
+    dbus::Bus* bus) {
+  return new NetworkChangeNotifierLinux(bus);
+}
+
+NetworkChangeNotifierLinux::NetworkChangeNotifierLinux(dbus::Bus* bus)
+    : notifier_thread_(new Thread(bus)) {
   // We create this notifier thread because the notification implementation
   // needs a MessageLoopForIO, and there's no guarantee that
   // MessageLoop::current() meets that criterion.
@@ -222,8 +446,7 @@ NetworkChangeNotifierLinux::~NetworkChangeNotifierLinux() {
 }
 
 bool NetworkChangeNotifierLinux::IsCurrentlyOffline() const {
-  // TODO(eroman): http://crbug.com/53473
-  return false;
+  return notifier_thread_->IsCurrentlyOffline();
 }
 
 }  // namespace net
diff --git a/net/base/network_change_notifier_linux.h b/net/base/network_change_notifier_linux.h
index 89b0545..083454f 100644
--- a/net/base/network_change_notifier_linux.h
+++ b/net/base/network_change_notifier_linux.h
@@ -11,15 +11,23 @@
 #include "base/memory/scoped_ptr.h"
 #include "net/base/network_change_notifier.h"
 
+namespace dbus {
+class Bus;
+}
+
 namespace net {
 
 class NetworkChangeNotifierLinux : public NetworkChangeNotifier {
  public:
-  NetworkChangeNotifierLinux();
+  static NetworkChangeNotifierLinux* Create();
+
+  // Unittests inject a mock bus.
+  static NetworkChangeNotifierLinux* CreateForTest(dbus::Bus* bus);
 
  private:
   class Thread;
 
+  explicit NetworkChangeNotifierLinux(dbus::Bus* bus);
   virtual ~NetworkChangeNotifierLinux();
 
   // NetworkChangeNotifier:
diff --git a/net/base/network_change_notifier_linux_unittest.cc b/net/base/network_change_notifier_linux_unittest.cc
new file mode 100644
index 0000000..c97092a
--- /dev/null
+++ b/net/base/network_change_notifier_linux_unittest.cc
@@ -0,0 +1,227 @@
+// Copyright (c) 2011 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/base/network_change_notifier_linux.h"
+
+#include "base/bind.h"
+#include "base/message_loop_proxy.h"
+#include "base/synchronization/waitable_event.h"
+#include "dbus/mock_bus.h"
+#include "dbus/mock_object_proxy.h"
+#include "dbus/message.h"
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace net {
+
+using testing::_;
+using testing::DoAll;
+using testing::InvokeWithoutArgs;
+using testing::Return;
+using testing::SaveArg;
+
+class NetworkChangeNotifierLinuxTest : public testing::Test {
+ protected:
+  // A subset of the NetworkManager-defined constants used in
+  // the tests below. See network_change_notifier_linux.cc
+  // for the full list.
+  enum {
+    NM_STATE_DISCONNECTED = 20,
+    NM_STATE_DISCONNECTING = 30,
+    NM_STATE_CONNECTED_SITE = 70,
+    NM_STATE_CONNECTED_GLOBAL = 70
+  };
+
+  NetworkChangeNotifierLinuxTest()
+      : initialized_(false, false) {}
+
+  virtual void SetUp() {
+    dbus::Bus::Options options;
+    options.bus_type = dbus::Bus::SYSTEM;
+    mock_bus_ = new dbus::MockBus(options);
+
+    mock_object_proxy_ = new dbus::MockObjectProxy(mock_bus_.get(),
+                                                   "service_name",
+                                                   "service_path");
+    EXPECT_CALL(*mock_bus_, GetObjectProxy(_, _))
+        .WillOnce(Return(mock_object_proxy_.get()));
+
+    EXPECT_CALL(*mock_object_proxy_, CallMethod(_, _, _))
+        .WillOnce(SaveArg<2>(&response_callback_));
+    EXPECT_CALL(*mock_object_proxy_, ConnectToSignal(_, _, _, _))
+        .WillOnce(
+            DoAll(
+                SaveArg<2>(&signal_callback_),
+                InvokeWithoutArgs(
+                    this,
+                    &NetworkChangeNotifierLinuxTest::Initialize)));
+
+    notifier_.reset(NetworkChangeNotifierLinux::CreateForTest(mock_bus_.get()));
+
+    initialized_.Wait();
+  }
+
+  void Initialize() {
+    notifier_thread_proxy_ = base::MessageLoopProxy::current();
+    initialized_.Signal();
+  }
+
+  void RunOnNotifierThread(const base::Closure& callback) {
+    base::WaitableEvent event(false, false);
+    notifier_thread_proxy_->PostTask(FROM_HERE, base::Bind(
+        &RunOnNotifierThreadHelper, callback, &event));
+    event.Wait();
+    // Run any tasks queued on the main thread, e.g. by
+    // ObserverListThreadSafe.
+    MessageLoop::current()->RunAllPending();
+  }
+
+  void SendResponse(uint32 state) {
+    scoped_ptr<dbus::Response> response(dbus::Response::CreateEmpty());
+    dbus::MessageWriter writer(response.get());
+    writer.AppendUint32(state);
+    RunOnNotifierThread(base::Bind(response_callback_, response.get()));
+  }
+
+  void SendSignal(uint32 state) {
+    dbus::Signal signal("org.freedesktop.NetworkManager", "StateChanged");
+    dbus::MessageWriter writer(&signal);
+    writer.AppendUint32(state);
+    RunOnNotifierThread(base::Bind(signal_callback_, &signal));
+  }
+
+  dbus::ObjectProxy::ResponseCallback response_callback_;
+  dbus::ObjectProxy::SignalCallback signal_callback_;
+
+  // Allows creating a new NetworkChangeNotifier.  Must be created before
+  // |notifier_| and destroyed after it to avoid DCHECK failures.
+  NetworkChangeNotifier::DisableForTest disable_for_test_;
+  scoped_ptr<NetworkChangeNotifier> notifier_;
+
+ private:
+  static void RunOnNotifierThreadHelper(const base::Closure& callback,
+                                        base::WaitableEvent* event) {
+    callback.Run();
+    event->Signal();
+  }
+
+  base::WaitableEvent initialized_;
+
+  // Valid only after initialized_ is signaled.
+  scoped_refptr<base::MessageLoopProxy> notifier_thread_proxy_;
+
+  scoped_refptr<dbus::MockBus> mock_bus_;
+  scoped_refptr<dbus::MockObjectProxy> mock_object_proxy_;
+};
+
+namespace {
+
+class OfflineObserver : public NetworkChangeNotifier::OnlineStateObserver {
+ public:
+  OfflineObserver()
+      : notification_count(0),
+        last_online_value(true) {
+    NetworkChangeNotifier::AddOnlineStateObserver(this);
+  }
+
+  ~OfflineObserver() {
+    NetworkChangeNotifier::RemoveOnlineStateObserver(this);
+  }
+
+  virtual void OnOnlineStateChanged(bool online) OVERRIDE {
+    notification_count++;
+    last_online_value = online;
+  }
+
+  int notification_count;
+  bool last_online_value;
+};
+
+TEST_F(NetworkChangeNotifierLinuxTest, Offline) {
+  SendResponse(NM_STATE_DISCONNECTED);
+  EXPECT_TRUE(NetworkChangeNotifier::IsOffline());
+}
+
+TEST_F(NetworkChangeNotifierLinuxTest, Online) {
+  SendResponse(NM_STATE_CONNECTED_GLOBAL);
+  EXPECT_FALSE(NetworkChangeNotifier::IsOffline());
+}
+
+TEST_F(NetworkChangeNotifierLinuxTest, OfflineThenOnline) {
+  OfflineObserver observer;
+
+  SendResponse(NM_STATE_DISCONNECTED);
+  EXPECT_TRUE(NetworkChangeNotifier::IsOffline());
+  EXPECT_EQ(0, observer.notification_count);
+
+  SendSignal(NM_STATE_CONNECTED_GLOBAL);
+  EXPECT_FALSE(NetworkChangeNotifier::IsOffline());
+  EXPECT_EQ(1, observer.notification_count);
+  EXPECT_TRUE(observer.last_online_value);
+}
+
+TEST_F(NetworkChangeNotifierLinuxTest, MultipleStateChanges) {
+  OfflineObserver observer;
+
+  SendResponse(NM_STATE_CONNECTED_GLOBAL);
+  EXPECT_FALSE(NetworkChangeNotifier::IsOffline());
+  EXPECT_EQ(0, observer.notification_count);
+
+  SendSignal(NM_STATE_DISCONNECTED);
+  EXPECT_TRUE(NetworkChangeNotifier::IsOffline());
+  EXPECT_EQ(1, observer.notification_count);
+  EXPECT_FALSE(observer.last_online_value);
+
+  SendSignal(NM_STATE_CONNECTED_GLOBAL);
+  EXPECT_FALSE(NetworkChangeNotifier::IsOffline());
+  EXPECT_EQ(2, observer.notification_count);
+  EXPECT_TRUE(observer.last_online_value);
+}
+
+TEST_F(NetworkChangeNotifierLinuxTest, IgnoreContinuedOnlineState) {
+  OfflineObserver observer;
+
+  SendResponse(NM_STATE_CONNECTED_SITE);
+  EXPECT_FALSE(NetworkChangeNotifier::IsOffline());
+  EXPECT_EQ(0, observer.notification_count);
+
+  SendSignal(NM_STATE_CONNECTED_GLOBAL);
+  EXPECT_FALSE(NetworkChangeNotifier::IsOffline());
+  EXPECT_EQ(0, observer.notification_count);
+}
+
+TEST_F(NetworkChangeNotifierLinuxTest, IgnoreContinuedOfflineState) {
+  OfflineObserver observer;
+
+  SendResponse(NM_STATE_DISCONNECTING);
+  EXPECT_TRUE(NetworkChangeNotifier::IsOffline());
+  EXPECT_EQ(0, observer.notification_count);
+
+  SendSignal(NM_STATE_DISCONNECTED);
+  EXPECT_TRUE(NetworkChangeNotifier::IsOffline());
+  EXPECT_EQ(0, observer.notification_count);
+}
+
+TEST_F(NetworkChangeNotifierLinuxTest, NullResponse) {
+  RunOnNotifierThread(base::Bind(
+      response_callback_, static_cast<dbus::Response*>(NULL)));
+  EXPECT_FALSE(NetworkChangeNotifier::IsOffline());
+}
+
+TEST_F(NetworkChangeNotifierLinuxTest, EmptyResponse) {
+  scoped_ptr<dbus::Response> response(dbus::Response::CreateEmpty());
+  RunOnNotifierThread(base::Bind(response_callback_, response.get()));
+  EXPECT_FALSE(NetworkChangeNotifier::IsOffline());
+}
+
+TEST_F(NetworkChangeNotifierLinuxTest, InvalidResponse) {
+  scoped_ptr<dbus::Response> response(dbus::Response::CreateEmpty());
+  dbus::MessageWriter writer(response.get());
+  writer.AppendUint16(20);  // Uint16 instead of the expected Uint32
+  RunOnNotifierThread(base::Bind(response_callback_, response.get()));
+  EXPECT_FALSE(NetworkChangeNotifier::IsOffline());
+}
+
+}  // namespace
+}  // namespace net
diff --git a/net/net.gyp b/net/net.gyp
index 628bb69..e0b467c 100644
--- a/net/net.gyp
+++ b/net/net.gyp
@@ -939,6 +939,13 @@
             ],
           },
         ],
+        [ 'OS == "linux"', {
+            'dependencies': [
+              '../build/linux/system.gyp:dbus',
+              '../dbus/dbus.gyp:dbus',
+            ],
+          },
+        ],
       ],
     },
     {
@@ -989,6 +996,7 @@
         'base/net_log_unittest.cc',
         'base/net_log_unittest.h',
         'base/net_util_unittest.cc',
+        'base/network_change_notifier_linux_unittest.cc',
         'base/network_change_notifier_win_unittest.cc',
         'base/origin_bound_cert_service_unittest.cc',
         'base/pem_tokenizer_unittest.cc',
@@ -1224,6 +1232,13 @@
             ],
           },
         ],
+        [ 'OS == "linux"', {
+            'dependencies': [
+              '../build/linux/system.gyp:dbus',
+              '../dbus/dbus.gyp:dbus_test_support',
+            ],
+          },
+        ],
       ],
     },
     {