Helper functions in NetworkChangeNotifier related to WWAN use

net/base/network_change_notifier.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NET_BASE_NETWORK_CHANGE_NOTIFIER_H_
 #define NET_BASE_NETWORK_CHANGE_NOTIFIER_H_
 
 #include "base/basictypes.h"
 #include "base/observer_list_threadsafe.h"
 #include "net/base/net_export.h"
@@ skipping 93 matching lines @@
   // threads try to access the API below, and it must outlive all other threads
   // which might try to use it.
   static NetworkChangeNotifier* Create();
 
   // Returns the connection type.
   // A return value of |CONNECTION_NONE| is a pretty strong indicator that the
   // user won't be able to connect to remote sites. However, another return
   // value doesn't imply that the user will be able to connect to remote sites;
   // even if some link is up, it is uncertain whether a particular connection
   // attempt to a particular remote site will be successful.
+  // The returned value only describes the connection currently used by the
+  // device, and does not take into account other machines on the network. For
+  // example, if the device is connected using Wifi to a 3G gateway to access
+  // the internet, the connection type is CONNECTION_WIFI.
   static ConnectionType GetConnectionType();
 
   // Retrieve the last read DnsConfig. This could be expensive if the system has
   // a large HOSTS file.
   static void GetDnsConfig(DnsConfig* config);
 
 #if defined(OS_LINUX)
   // Returns the AddressTrackerLinux if present.
   static const internal::AddressTrackerLinux* GetAddressTracker();
 #endif
 
   // Convenience method to determine if the user is offline.
   // Returns true if there is currently no internet connection.
   //
   // A return value of |true| is a pretty strong indicator that the user
   // won't be able to connect to remote sites. However, a return value of
   // |false| is inconclusive; even if some link is up, it is uncertain
   // whether a particular connection attempt to a particular remote site
   // will be successfully.
-  static bool IsOffline() {
-    return GetConnectionType() == CONNECTION_NONE;
-  }
+  static bool IsOffline();
+
+  // Returns true if |type| is a cellular connection.
+  // Returns false if |type| is CONNECTION_UNKNOWN, and thus, depending on the
+  // implementation of GetConnectionType(), it is possible that
+  // IsConnectionCellular(GetConnectionType()) returns false even if the
+  // current connection is cellular.
+  static bool IsConnectionCellular(ConnectionType type);
 
   // Like Create(), but for use in tests.  The mock object doesn't monitor any
   // events, it merely rebroadcasts notifications when requested.
   static NetworkChangeNotifier* CreateMock();
 
   // Registers |observer| to receive notifications of network changes.  The
   // thread on which this is called is the thread on which |observer| will be
   // called back with notifications.  This is safe to call if Create() has not
   // been called (as long as it doesn't race the Create() call on another
   // thread), in which case it will simply do nothing.
@@ skipping 83 matching lines @@
 
   // A little-piggy-back observer that simply logs UMA histogram data.
   scoped_ptr<HistogramWatcher> histogram_watcher_;
 
   DISALLOW_COPY_AND_ASSIGN(NetworkChangeNotifier);
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_NETWORK_CHANGE_NOTIFIER_H_