src/net/base/network_change_notifier.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "net/base/network_change_notifier.h"
   6
   7 #include "base/metrics/histogram.h"
   8 #include "base/synchronization/lock.h"
   9 #include "build/build_config.h"
  10 #include "net/base/net_util.h"
  11 #include "net/base/network_change_notifier_factory.h"
  12 #include "net/dns/dns_config_service.h"
  13 #include "net/url_request/url_request.h"
  14 #include "url/gurl.h"
  15
  16 #if defined(OS_WIN)
  17 #include "net/base/network_change_notifier_win.h"
  18 #elif defined(OS_LINUX) && !defined(OS_CHROMEOS)
  19 #include "net/base/network_change_notifier_linux.h"
  20 #elif defined(OS_MACOSX)
  21 #include "net/base/network_change_notifier_mac.h"
  22 #endif
  23
  24 namespace net {
  25
  26 namespace {
  27
  28 // The actual singleton notifier.  The class contract forbids usage of the API
  29 // in ways that would require us to place locks around access to this object.
  30 // (The prohibition on global non-POD objects makes it tricky to do such a thing
  31 // anyway.)
  32 NetworkChangeNotifier* g_network_change_notifier = NULL;
  33
  34 // Class factory singleton.
  35 NetworkChangeNotifierFactory* g_network_change_notifier_factory = NULL;
  36
  37 class MockNetworkChangeNotifier : public NetworkChangeNotifier {
  38  public:
  39   virtual ConnectionType GetCurrentConnectionType() const OVERRIDE {
  40     return CONNECTION_UNKNOWN;
  41   }
  42 };
  43
  44 }  // namespace
  45
  46 // The main observer class that records UMAs for network events.
  47 class HistogramWatcher
  48     : public NetworkChangeNotifier::ConnectionTypeObserver,
  49       public NetworkChangeNotifier::IPAddressObserver,
  50       public NetworkChangeNotifier::DNSObserver,
  51       public NetworkChangeNotifier::NetworkChangeObserver {
  52  public:
  53   HistogramWatcher()
  54       : last_ip_address_change_(base::TimeTicks::Now()),
  55         last_connection_change_(base::TimeTicks::Now()),
  56         last_dns_change_(base::TimeTicks::Now()),
  57         last_network_change_(base::TimeTicks::Now()),
  58         last_connection_type_(NetworkChangeNotifier::CONNECTION_UNKNOWN),
  59         offline_packets_received_(0),
  60         bytes_read_since_last_connection_change_(0),
  61         peak_kbps_since_last_connection_change_(0) {}
  62
  63   // Registers our three Observer implementations.  This is called from the
  64   // network thread so that our Observer implementations are also called
  65   // from the network thread.  This avoids multi-threaded race conditions
  66   // because the only other interface, |NotifyDataReceived| is also
  67   // only called from the network thread.
  68   void Init() {
  69     NetworkChangeNotifier::AddConnectionTypeObserver(this);
  70     NetworkChangeNotifier::AddIPAddressObserver(this);
  71     NetworkChangeNotifier::AddDNSObserver(this);
  72     NetworkChangeNotifier::AddNetworkChangeObserver(this);
  73   }
  74
  75   virtual ~HistogramWatcher() {}
  76
  77   // NetworkChangeNotifier::IPAddressObserver implementation.
  78   virtual void OnIPAddressChanged() OVERRIDE {
  79     UMA_HISTOGRAM_MEDIUM_TIMES("NCN.IPAddressChange",
  80                                SinceLast(&last_ip_address_change_));
  81     UMA_HISTOGRAM_MEDIUM_TIMES(
  82         "NCN.ConnectionTypeChangeToIPAddressChange",
  83         last_ip_address_change_ - last_connection_change_);
  84   }
  85
  86   // NetworkChangeNotifier::ConnectionTypeObserver implementation.
  87   virtual void OnConnectionTypeChanged(
  88       NetworkChangeNotifier::ConnectionType type) OVERRIDE {
  89     base::TimeTicks now = base::TimeTicks::Now();
  90     int32 kilobytes_read = bytes_read_since_last_connection_change_ / 1000;
  91     base::TimeDelta state_duration = SinceLast(&last_connection_change_);
  92     if (bytes_read_since_last_connection_change_) {
  93       switch (last_connection_type_) {
  94         case NetworkChangeNotifier::CONNECTION_UNKNOWN:
  95           UMA_HISTOGRAM_TIMES("NCN.CM.FirstReadOnUnknown",
  96                               first_byte_after_connection_change_);
  97           UMA_HISTOGRAM_TIMES("NCN.CM.FastestRTTOnUnknown",
  98                               fastest_RTT_since_last_connection_change_);
  99           break;
 100         case NetworkChangeNotifier::CONNECTION_ETHERNET:
 101           UMA_HISTOGRAM_TIMES("NCN.CM.FirstReadOnEthernet",
 102                               first_byte_after_connection_change_);
 103           UMA_HISTOGRAM_TIMES("NCN.CM.FastestRTTOnEthernet",
 104                               fastest_RTT_since_last_connection_change_);
 105           break;
 106         case NetworkChangeNotifier::CONNECTION_WIFI:
 107           UMA_HISTOGRAM_TIMES("NCN.CM.FirstReadOnWifi",
 108                               first_byte_after_connection_change_);
 109           UMA_HISTOGRAM_TIMES("NCN.CM.FastestRTTOnWifi",
 110                               fastest_RTT_since_last_connection_change_);
 111           break;
 112         case NetworkChangeNotifier::CONNECTION_2G:
 113           UMA_HISTOGRAM_TIMES("NCN.CM.FirstReadOn2G",
 114                               first_byte_after_connection_change_);
 115           UMA_HISTOGRAM_TIMES("NCN.CM.FastestRTTOn2G",
 116                               fastest_RTT_since_last_connection_change_);
 117           break;
 118         case NetworkChangeNotifier::CONNECTION_3G:
 119           UMA_HISTOGRAM_TIMES("NCN.CM.FirstReadOn3G",
 120                               first_byte_after_connection_change_);
 121           UMA_HISTOGRAM_TIMES("NCN.CM.FastestRTTOn3G",
 122                               fastest_RTT_since_last_connection_change_);
 123           break;
 124         case NetworkChangeNotifier::CONNECTION_4G:
 125           UMA_HISTOGRAM_TIMES("NCN.CM.FirstReadOn4G",
 126                               first_byte_after_connection_change_);
 127           UMA_HISTOGRAM_TIMES("NCN.CM.FastestRTTOn4G",
 128                               fastest_RTT_since_last_connection_change_);
 129           break;
 130         case NetworkChangeNotifier::CONNECTION_NONE:
 131           UMA_HISTOGRAM_TIMES("NCN.CM.FirstReadOnNone",
 132                               first_byte_after_connection_change_);
 133           UMA_HISTOGRAM_TIMES("NCN.CM.FastestRTTOnNone",
 134                               fastest_RTT_since_last_connection_change_);
 135           break;
 136       }
 137     }
 138     if (peak_kbps_since_last_connection_change_) {
 139       switch (last_connection_type_) {
 140         case NetworkChangeNotifier::CONNECTION_UNKNOWN:
 141           UMA_HISTOGRAM_COUNTS("NCN.CM.PeakKbpsOnUnknown",
 142                                peak_kbps_since_last_connection_change_);
 143           break;
 144         case NetworkChangeNotifier::CONNECTION_ETHERNET:
 145           UMA_HISTOGRAM_COUNTS("NCN.CM.PeakKbpsOnEthernet",
 146                                peak_kbps_since_last_connection_change_);
 147           break;
 148         case NetworkChangeNotifier::CONNECTION_WIFI:
 149           UMA_HISTOGRAM_COUNTS("NCN.CM.PeakKbpsOnWifi",
 150                                peak_kbps_since_last_connection_change_);
 151           break;
 152         case NetworkChangeNotifier::CONNECTION_2G:
 153           UMA_HISTOGRAM_COUNTS("NCN.CM.PeakKbpsOn2G",
 154                                peak_kbps_since_last_connection_change_);
 155           break;
 156         case NetworkChangeNotifier::CONNECTION_3G:
 157           UMA_HISTOGRAM_COUNTS("NCN.CM.PeakKbpsOn3G",
 158                                peak_kbps_since_last_connection_change_);
 159           break;
 160         case NetworkChangeNotifier::CONNECTION_4G:
 161           UMA_HISTOGRAM_COUNTS("NCN.CM.PeakKbpsOn4G",
 162                                peak_kbps_since_last_connection_change_);
 163           break;
 164         case NetworkChangeNotifier::CONNECTION_NONE:
 165           UMA_HISTOGRAM_COUNTS("NCN.CM.PeakKbpsOnNone",
 166                                peak_kbps_since_last_connection_change_);
 167           break;
 168       }
 169     }
 170     switch (last_connection_type_) {
 171       case NetworkChangeNotifier::CONNECTION_UNKNOWN:
 172         UMA_HISTOGRAM_LONG_TIMES("NCN.CM.TimeOnUnknown", state_duration);
 173         UMA_HISTOGRAM_COUNTS("NCN.CM.KBTransferedOnUnknown", kilobytes_read);
 174         break;
 175       case NetworkChangeNotifier::CONNECTION_ETHERNET:
 176         UMA_HISTOGRAM_LONG_TIMES("NCN.CM.TimeOnEthernet", state_duration);
 177         UMA_HISTOGRAM_COUNTS("NCN.CM.KBTransferedOnEthernet", kilobytes_read);
 178         break;
 179       case NetworkChangeNotifier::CONNECTION_WIFI:
 180         UMA_HISTOGRAM_LONG_TIMES("NCN.CM.TimeOnWifi", state_duration);
 181         UMA_HISTOGRAM_COUNTS("NCN.CM.KBTransferedOnWifi", kilobytes_read);
 182         break;
 183       case NetworkChangeNotifier::CONNECTION_2G:
 184         UMA_HISTOGRAM_LONG_TIMES("NCN.CM.TimeOn2G", state_duration);
 185         UMA_HISTOGRAM_COUNTS("NCN.CM.KBTransferedOn2G", kilobytes_read);
 186         break;
 187       case NetworkChangeNotifier::CONNECTION_3G:
 188         UMA_HISTOGRAM_LONG_TIMES("NCN.CM.TimeOn3G", state_duration);
 189         UMA_HISTOGRAM_COUNTS("NCN.CM.KBTransferedOn3G", kilobytes_read);
 190         break;
 191       case NetworkChangeNotifier::CONNECTION_4G:
 192         UMA_HISTOGRAM_LONG_TIMES("NCN.CM.TimeOn4G", state_duration);
 193         UMA_HISTOGRAM_COUNTS("NCN.CM.KBTransferedOn4G", kilobytes_read);
 194         break;
 195       case NetworkChangeNotifier::CONNECTION_NONE:
 196         UMA_HISTOGRAM_LONG_TIMES("NCN.CM.TimeOnNone", state_duration);
 197         UMA_HISTOGRAM_COUNTS("NCN.CM.KBTransferedOnNone", kilobytes_read);
 198         break;
 199     }
 200
 201     if (type != NetworkChangeNotifier::CONNECTION_NONE) {
 202       UMA_HISTOGRAM_MEDIUM_TIMES("NCN.OnlineChange", state_duration);
 203
 204       if (offline_packets_received_) {
 205         if ((now - last_offline_packet_received_) <
 206             base::TimeDelta::FromSeconds(5)) {
 207           // We can compare this sum with the sum of NCN.OfflineDataRecv.
 208           UMA_HISTOGRAM_COUNTS_10000(
 209               "NCN.OfflineDataRecvAny5sBeforeOnline",
 210               offline_packets_received_);
 211         }
 212
 213         UMA_HISTOGRAM_MEDIUM_TIMES("NCN.OfflineDataRecvUntilOnline",
 214                                    now - last_offline_packet_received_);
 215       }
 216     } else {
 217       UMA_HISTOGRAM_MEDIUM_TIMES("NCN.OfflineChange", state_duration);
 218     }
 219     UMA_HISTOGRAM_MEDIUM_TIMES(
 220         "NCN.IPAddressChangeToConnectionTypeChange",
 221         now - last_ip_address_change_);
 222
 223     offline_packets_received_ = 0;
 224     bytes_read_since_last_connection_change_ = 0;
 225     peak_kbps_since_last_connection_change_ = 0;
 226     last_connection_type_ = type;
 227     polling_interval_ = base::TimeDelta::FromSeconds(1);
 228   }
 229
 230   // NetworkChangeNotifier::DNSObserver implementation.
 231   virtual void OnDNSChanged() OVERRIDE {
 232     UMA_HISTOGRAM_MEDIUM_TIMES("NCN.DNSConfigChange",
 233                                SinceLast(&last_dns_change_));
 234   }
 235
 236   // NetworkChangeNotifier::NetworkChangeObserver implementation.
 237   virtual void OnNetworkChanged(
 238       NetworkChangeNotifier::ConnectionType type) OVERRIDE {
 239     if (type != NetworkChangeNotifier::CONNECTION_NONE) {
 240       UMA_HISTOGRAM_MEDIUM_TIMES("NCN.NetworkOnlineChange",
 241                                  SinceLast(&last_network_change_));
 242     } else {
 243       UMA_HISTOGRAM_MEDIUM_TIMES("NCN.NetworkOfflineChange",
 244                                  SinceLast(&last_network_change_));
 245     }
 246   }
 247
 248   // Record histogram data whenever we receive a packet. Should only be called
 249   // from the network thread.
 250   void NotifyDataReceived(const URLRequest& request, int bytes_read) {
 251     if (IsLocalhost(request.url().host()) ||
 252         !request.url().SchemeIsHTTPOrHTTPS()) {
 253       return;
 254     }
 255
 256     base::TimeTicks now = base::TimeTicks::Now();
 257     base::TimeDelta request_duration = now - request.creation_time();
 258     if (bytes_read_since_last_connection_change_ == 0) {
 259       first_byte_after_connection_change_ = now - last_connection_change_;
 260       fastest_RTT_since_last_connection_change_ = request_duration;
 261     }
 262     bytes_read_since_last_connection_change_ += bytes_read;
 263     if (request_duration < fastest_RTT_since_last_connection_change_)
 264       fastest_RTT_since_last_connection_change_ = request_duration;
 265     // Ignore tiny transfers which will not produce accurate rates.
 266     // Ignore zero duration transfers which might cause divide by zero.
 267     if (bytes_read > 10000 &&
 268         request_duration > base::TimeDelta::FromMilliseconds(1) &&
 269         request.creation_time() > last_connection_change_) {
 270       int32 kbps = bytes_read * 8 / request_duration.InMilliseconds();
 271       if (kbps > peak_kbps_since_last_connection_change_)
 272         peak_kbps_since_last_connection_change_ = kbps;
 273     }
 274
 275     if (last_connection_type_ != NetworkChangeNotifier::CONNECTION_NONE)
 276       return;
 277
 278     UMA_HISTOGRAM_MEDIUM_TIMES("NCN.OfflineDataRecv",
 279                                now - last_connection_change_);
 280     offline_packets_received_++;
 281     last_offline_packet_received_ = now;
 282
 283     if ((now - last_polled_connection_) > polling_interval_) {
 284       polling_interval_ *= 2;
 285       last_polled_connection_ = now;
 286       last_polled_connection_type_ =
 287           NetworkChangeNotifier::GetConnectionType();
 288     }
 289     if (last_polled_connection_type_ ==
 290         NetworkChangeNotifier::CONNECTION_NONE) {
 291       UMA_HISTOGRAM_MEDIUM_TIMES("NCN.PollingOfflineDataRecv",
 292                                  now - last_connection_change_);
 293     }
 294   }
 295
 296  private:
 297   static base::TimeDelta SinceLast(base::TimeTicks *last_time) {
 298     base::TimeTicks current_time = base::TimeTicks::Now();
 299     base::TimeDelta delta = current_time - *last_time;
 300     *last_time = current_time;
 301     return delta;
 302   }
 303
 304   base::TimeTicks last_ip_address_change_;
 305   base::TimeTicks last_connection_change_;
 306   base::TimeTicks last_dns_change_;
 307   base::TimeTicks last_network_change_;
 308   base::TimeTicks last_offline_packet_received_;
 309   base::TimeTicks last_polled_connection_;
 310   // |polling_interval_| is initialized by |OnConnectionTypeChanged| on our
 311   // first transition to offline and on subsequent transitions.  Once offline,
 312   // |polling_interval_| doubles as offline data is received and we poll
 313   // with |NetworkChangeNotifier::GetConnectionType| to verify the connection
 314   // state.
 315   base::TimeDelta polling_interval_;
 316   // |last_connection_type_| is the last value passed to
 317   // |OnConnectionTypeChanged|.
 318   NetworkChangeNotifier::ConnectionType last_connection_type_;
 319   // |last_polled_connection_type_| is last result from calling
 320   // |NetworkChangeNotifier::GetConnectionType| in |NotifyDataReceived|.
 321   NetworkChangeNotifier::ConnectionType last_polled_connection_type_;
 322   // Count of how many times NotifyDataReceived() has been called while the
 323   // NetworkChangeNotifier thought network connection was offline.
 324   int32 offline_packets_received_;
 325   // Number of bytes of network data received since last connectivity change.
 326   int32 bytes_read_since_last_connection_change_;
 327   // Fastest round-trip-time (RTT) since last connectivity change. RTT measured
 328   // from URLRequest creation until first byte received.
 329   base::TimeDelta fastest_RTT_since_last_connection_change_;
 330   // Time between connectivity change and first network data byte received.
 331   base::TimeDelta first_byte_after_connection_change_;
 332   // Rough measurement of peak KB/s witnessed since last connectivity change.
 333   // The accuracy is decreased by ignoring these factors:
 334   // 1) Multiple URLRequests can occur concurrently.
 335   // 2) NotifyDataReceived() may be called repeatedly for one URLRequest.
 336   // 3) The transfer time includes at least one RTT while no bytes are read.
 337   // Erring on the conservative side is hopefully offset by taking the maximum.
 338   int32 peak_kbps_since_last_connection_change_;
 339
 340   DISALLOW_COPY_AND_ASSIGN(HistogramWatcher);
 341 };
 342
 343 // NetworkState is thread safe.
 344 class NetworkChangeNotifier::NetworkState {
 345  public:
 346   NetworkState() {}
 347   ~NetworkState() {}
 348
 349   void GetDnsConfig(DnsConfig* config) const {
 350     base::AutoLock lock(lock_);
 351     *config = dns_config_;
 352   }
 353
 354   void SetDnsConfig(const DnsConfig& dns_config) {
 355     base::AutoLock lock(lock_);
 356     dns_config_ = dns_config;
 357   }
 358
 359  private:
 360   mutable base::Lock lock_;
 361   DnsConfig dns_config_;
 362 };
 363
 364 NetworkChangeNotifier::NetworkChangeCalculatorParams::
 365     NetworkChangeCalculatorParams() {
 366 }
 367
 368 // Calculates NetworkChange signal from IPAddress and ConnectionType signals.
 369 class NetworkChangeNotifier::NetworkChangeCalculator
 370     : public ConnectionTypeObserver,
 371       public IPAddressObserver {
 372  public:
 373   NetworkChangeCalculator(const NetworkChangeCalculatorParams& params)
 374       : params_(params),
 375         have_announced_(false),
 376         last_announced_connection_type_(CONNECTION_NONE),
 377         pending_connection_type_(CONNECTION_NONE) {}
 378
 379   void Init() {
 380     AddConnectionTypeObserver(this);
 381     AddIPAddressObserver(this);
 382   }
 383
 384   virtual ~NetworkChangeCalculator() {
 385     RemoveConnectionTypeObserver(this);
 386     RemoveIPAddressObserver(this);
 387   }
 388
 389   // NetworkChangeNotifier::IPAddressObserver implementation.
 390   virtual void OnIPAddressChanged() OVERRIDE {
 391     base::TimeDelta delay = last_announced_connection_type_ == CONNECTION_NONE
 392         ? params_.ip_address_offline_delay_ : params_.ip_address_online_delay_;
 393     // Cancels any previous timer.
 394     timer_.Start(FROM_HERE, delay, this, &NetworkChangeCalculator::Notify);
 395   }
 396
 397   // NetworkChangeNotifier::ConnectionTypeObserver implementation.
 398   virtual void OnConnectionTypeChanged(ConnectionType type) OVERRIDE {
 399     pending_connection_type_ = type;
 400     base::TimeDelta delay = last_announced_connection_type_ == CONNECTION_NONE
 401         ? params_.connection_type_offline_delay_
 402         : params_.connection_type_online_delay_;
 403     // Cancels any previous timer.
 404     timer_.Start(FROM_HERE, delay, this, &NetworkChangeCalculator::Notify);
 405   }
 406
 407  private:
 408   void Notify() {
 409     // Don't bother signaling about dead connections.
 410     if (have_announced_ &&
 411         (last_announced_connection_type_ == CONNECTION_NONE) &&
 412         (pending_connection_type_ == CONNECTION_NONE)) {
 413       return;
 414     }
 415     have_announced_ = true;
 416     last_announced_connection_type_ = pending_connection_type_;
 417     // Immediately before sending out an online signal, send out an offline
 418     // signal to perform any destructive actions before constructive actions.
 419     if (pending_connection_type_ != CONNECTION_NONE)
 420       NetworkChangeNotifier::NotifyObserversOfNetworkChange(CONNECTION_NONE);
 421     NetworkChangeNotifier::NotifyObserversOfNetworkChange(
 422         pending_connection_type_);
 423   }
 424
 425   const NetworkChangeCalculatorParams params_;
 426
 427   // Indicates if NotifyObserversOfNetworkChange has been called yet.
 428   bool have_announced_;
 429   // Last value passed to NotifyObserversOfNetworkChange.
 430   ConnectionType last_announced_connection_type_;
 431   // Value to pass to NotifyObserversOfNetworkChange when Notify is called.
 432   ConnectionType pending_connection_type_;
 433   // Used to delay notifications so duplicates can be combined.
 434   base::OneShotTimer<NetworkChangeCalculator> timer_;
 435 };
 436
 437 NetworkChangeNotifier::~NetworkChangeNotifier() {
 438   DCHECK_EQ(this, g_network_change_notifier);
 439   g_network_change_notifier = NULL;
 440 }
 441
 442 // static
 443 void NetworkChangeNotifier::SetFactory(
 444     NetworkChangeNotifierFactory* factory) {
 445   CHECK(!g_network_change_notifier_factory);
 446   g_network_change_notifier_factory = factory;
 447 }
 448
 449 // static
 450 NetworkChangeNotifier* NetworkChangeNotifier::Create() {
 451   if (g_network_change_notifier_factory)
 452     return g_network_change_notifier_factory->CreateInstance();
 453
 454 #if defined(OS_WIN)
 455   NetworkChangeNotifierWin* network_change_notifier =
 456       new NetworkChangeNotifierWin();
 457   network_change_notifier->WatchForAddressChange();
 458   return network_change_notifier;
 459 #elif defined(OS_CHROMEOS) || defined(OS_ANDROID)
 460   // ChromeOS and Android builds MUST use their own class factory.
 461 #if !defined(OS_CHROMEOS)
 462   // TODO(oshima): ash_shell do not have access to chromeos'es
 463   // notifier yet. Re-enable this when chromeos'es notifier moved to
 464   // chromeos root directory. crbug.com/119298.
 465   CHECK(false);
 466 #endif
 467   return NULL;
 468 #elif defined(OS_LINUX)
 469   return NetworkChangeNotifierLinux::Create();
 470 #elif defined(OS_MACOSX)
 471   return new NetworkChangeNotifierMac();
 472 #else
 473   NOTIMPLEMENTED();
 474   return NULL;
 475 #endif
 476 }
 477
 478 // static
 479 NetworkChangeNotifier::ConnectionType
 480 NetworkChangeNotifier::GetConnectionType() {
 481   return g_network_change_notifier ?
 482       g_network_change_notifier->GetCurrentConnectionType() :
 483       CONNECTION_UNKNOWN;
 484 }
 485
 486 // static
 487 void NetworkChangeNotifier::GetDnsConfig(DnsConfig* config) {
 488   if (!g_network_change_notifier) {
 489     *config = DnsConfig();
 490   } else {
 491     g_network_change_notifier->network_state_->GetDnsConfig(config);
 492   }
 493 }
 494
 495 // static
 496 const char* NetworkChangeNotifier::ConnectionTypeToString(
 497     ConnectionType type) {
 498   static const char* kConnectionTypeNames[] = {
 499     "CONNECTION_UNKNOWN",
 500     "CONNECTION_ETHERNET",
 501     "CONNECTION_WIFI",
 502     "CONNECTION_2G",
 503     "CONNECTION_3G",
 504     "CONNECTION_4G",
 505     "CONNECTION_NONE"
 506   };
 507   COMPILE_ASSERT(
 508       arraysize(kConnectionTypeNames) ==
 509           NetworkChangeNotifier::CONNECTION_NONE + 1,
 510       ConnectionType_name_count_mismatch);
 511   if (type < CONNECTION_UNKNOWN || type > CONNECTION_NONE) {
 512     NOTREACHED();
 513     return "CONNECTION_INVALID";
 514   }
 515   return kConnectionTypeNames[type];
 516 }
 517
 518 // static
 519 void NetworkChangeNotifier::NotifyDataReceived(const URLRequest& request,
 520                                                int bytes_read) {
 521   if (!g_network_change_notifier)
 522     return;
 523   g_network_change_notifier->histogram_watcher_->NotifyDataReceived(request,
 524                                                                     bytes_read);
 525 }
 526
 527 // static
 528 void NetworkChangeNotifier::InitHistogramWatcher() {
 529   if (!g_network_change_notifier)
 530     return;
 531   g_network_change_notifier->histogram_watcher_->Init();
 532 }
 533
 534 #if defined(OS_LINUX)
 535 // static
 536 const internal::AddressTrackerLinux*
 537 NetworkChangeNotifier::GetAddressTracker() {
 538   return g_network_change_notifier ?
 539         g_network_change_notifier->GetAddressTrackerInternal() : NULL;
 540 }
 541 #endif
 542
 543 // static
 544 bool NetworkChangeNotifier::IsOffline() {
 545    return GetConnectionType() == CONNECTION_NONE;
 546 }
 547
 548 // static
 549 bool NetworkChangeNotifier::IsConnectionCellular(ConnectionType type) {
 550   bool is_cellular = false;
 551   switch (type) {
 552     case CONNECTION_2G:
 553     case CONNECTION_3G:
 554     case CONNECTION_4G:
 555       is_cellular =  true;
 556       break;
 557     case CONNECTION_UNKNOWN:
 558     case CONNECTION_ETHERNET:
 559     case CONNECTION_WIFI:
 560     case CONNECTION_NONE:
 561       is_cellular = false;
 562       break;
 563   }
 564   return is_cellular;
 565 }
 566
 567 // static
 568 NetworkChangeNotifier* NetworkChangeNotifier::CreateMock() {
 569   return new MockNetworkChangeNotifier();
 570 }
 571
 572 void NetworkChangeNotifier::AddIPAddressObserver(IPAddressObserver* observer) {
 573   if (g_network_change_notifier)
 574     g_network_change_notifier->ip_address_observer_list_->AddObserver(observer);
 575 }
 576
 577 void NetworkChangeNotifier::AddConnectionTypeObserver(
 578     ConnectionTypeObserver* observer) {
 579   if (g_network_change_notifier) {
 580     g_network_change_notifier->connection_type_observer_list_->AddObserver(
 581         observer);
 582   }
 583 }
 584
 585 void NetworkChangeNotifier::AddDNSObserver(DNSObserver* observer) {
 586   if (g_network_change_notifier) {
 587     g_network_change_notifier->resolver_state_observer_list_->AddObserver(
 588         observer);
 589   }
 590 }
 591
 592 void NetworkChangeNotifier::AddNetworkChangeObserver(
 593     NetworkChangeObserver* observer) {
 594   if (g_network_change_notifier) {
 595     g_network_change_notifier->network_change_observer_list_->AddObserver(
 596         observer);
 597   }
 598 }
 599
 600 void NetworkChangeNotifier::RemoveIPAddressObserver(
 601     IPAddressObserver* observer) {
 602   if (g_network_change_notifier) {
 603     g_network_change_notifier->ip_address_observer_list_->RemoveObserver(
 604         observer);
 605   }
 606 }
 607
 608 void NetworkChangeNotifier::RemoveConnectionTypeObserver(
 609     ConnectionTypeObserver* observer) {
 610   if (g_network_change_notifier) {
 611     g_network_change_notifier->connection_type_observer_list_->RemoveObserver(
 612         observer);
 613   }
 614 }
 615
 616 void NetworkChangeNotifier::RemoveDNSObserver(DNSObserver* observer) {
 617   if (g_network_change_notifier) {
 618     g_network_change_notifier->resolver_state_observer_list_->RemoveObserver(
 619         observer);
 620   }
 621 }
 622
 623 void NetworkChangeNotifier::RemoveNetworkChangeObserver(
 624     NetworkChangeObserver* observer) {
 625   if (g_network_change_notifier) {
 626     g_network_change_notifier->network_change_observer_list_->RemoveObserver(
 627         observer);
 628   }
 629 }
 630
 631 NetworkChangeNotifier::NetworkChangeNotifier(
 632     const NetworkChangeCalculatorParams& params
 633         /*= NetworkChangeCalculatorParams()*/)
 634     : ip_address_observer_list_(
 635         new ObserverListThreadSafe<IPAddressObserver>(
 636             ObserverListBase<IPAddressObserver>::NOTIFY_EXISTING_ONLY)),
 637       connection_type_observer_list_(
 638         new ObserverListThreadSafe<ConnectionTypeObserver>(
 639             ObserverListBase<ConnectionTypeObserver>::NOTIFY_EXISTING_ONLY)),
 640       resolver_state_observer_list_(
 641         new ObserverListThreadSafe<DNSObserver>(
 642             ObserverListBase<DNSObserver>::NOTIFY_EXISTING_ONLY)),
 643       network_change_observer_list_(
 644         new ObserverListThreadSafe<NetworkChangeObserver>(
 645             ObserverListBase<NetworkChangeObserver>::NOTIFY_EXISTING_ONLY)),
 646       network_state_(new NetworkState()),
 647       histogram_watcher_(new HistogramWatcher()),
 648       network_change_calculator_(new NetworkChangeCalculator(params)) {
 649   DCHECK(!g_network_change_notifier);
 650   g_network_change_notifier = this;
 651   network_change_calculator_->Init();
 652 }
 653
 654 #if defined(OS_LINUX)
 655 const internal::AddressTrackerLinux*
 656 NetworkChangeNotifier::GetAddressTrackerInternal() const {
 657   return NULL;
 658 }
 659 #endif
 660
 661 // static
 662 void NetworkChangeNotifier::NotifyObserversOfIPAddressChange() {
 663   if (g_network_change_notifier) {
 664     g_network_change_notifier->ip_address_observer_list_->Notify(
 665         &IPAddressObserver::OnIPAddressChanged);
 666   }
 667 }
 668
 669 // static
 670 void NetworkChangeNotifier::NotifyObserversOfDNSChange() {
 671   if (g_network_change_notifier) {
 672     g_network_change_notifier->resolver_state_observer_list_->Notify(
 673         &DNSObserver::OnDNSChanged);
 674   }
 675 }
 676
 677 // static
 678 void NetworkChangeNotifier::SetDnsConfig(const DnsConfig& config) {
 679   if (!g_network_change_notifier)
 680     return;
 681   g_network_change_notifier->network_state_->SetDnsConfig(config);
 682   NotifyObserversOfDNSChange();
 683 }
 684
 685 void NetworkChangeNotifier::NotifyObserversOfConnectionTypeChange() {
 686   if (g_network_change_notifier) {
 687     g_network_change_notifier->connection_type_observer_list_->Notify(
 688         &ConnectionTypeObserver::OnConnectionTypeChanged,
 689         GetConnectionType());
 690   }
 691 }
 692
 693 void NetworkChangeNotifier::NotifyObserversOfNetworkChange(
 694     ConnectionType type) {
 695   if (g_network_change_notifier) {
 696     g_network_change_notifier->network_change_observer_list_->Notify(
 697         &NetworkChangeObserver::OnNetworkChanged,
 698         type);
 699   }
 700 }
 701
 702 NetworkChangeNotifier::DisableForTest::DisableForTest()
 703     : network_change_notifier_(g_network_change_notifier) {
 704   DCHECK(g_network_change_notifier);
 705   g_network_change_notifier = NULL;
 706 }
 707
 708 NetworkChangeNotifier::DisableForTest::~DisableForTest() {
 709   DCHECK(!g_network_change_notifier);
 710   g_network_change_notifier = network_change_notifier_;
 711 }
 712
 713 }  // namespace net