Expose connection subtype from NetworkChangeNotifier

net/base/network_change_notifier.h

Index: net/base/network_change_notifier.h
diff --git a/net/base/network_change_notifier.h b/net/base/network_change_notifier.h
index 1cefe85ff6e15b29af41828e90157e4bd81b15d6..e71b7b3a1e832cf80427a94f18c8cf3c23e92d1e 100644
--- a/net/base/network_change_notifier.h
+++ b/net/base/network_change_notifier.h
@@ -276,6 +276,13 @@ class NET_EXPORT NetworkChangeNotifier {
   // the internet, the connection type is CONNECTION_WIFI.
   static ConnectionType GetConnectionType();
 
+  // Returns the connection subtype of the network the client is connected to.

[pauljensen, 2017/03/24 18:38:58]

"the connection subtype of the network the client is connected to"->"the
device's current default active network connection's subtype"

[tbansal1, 2017/03/24 23:22:24]

Done.

+  // 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.

[pauljensen, 2017/03/24 18:38:58]

there is no sub-type for WiFi

[pauljensen, 2017/03/24 18:38:59]

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.
->
The returned value only describes the first-hop connection, for example if the
device is connected via WiFi to a 4G hotspot, the returned value will reflect
WiFi, not 4G.

(Also please make this same replacement on line 273, but use
CONNECTION_WIFI_there.)

[tbansal1, 2017/03/24 23:22:24]

Thanks, I am more interested in cellular. If it proves useful, I may work on
getting the subtype for WiFi, although IIRC, there are some issues there due to
Android permissions.

I have added one more statement to explain that this may return UNKNOWN more
frequently. Let me know if it needs to be reworded.

[tbansal1, 2017/03/24 23:22:24]

Done.

+  static ConnectionSubtype GetConnectionSubtype();
+
   // Sets |max_bandwidth_mbps| to a theoretical upper limit on download
   // bandwidth, potentially based on underlying connection type, signal
   // strength, or some other signal. If the network subtype is unknown then
@@ -498,6 +505,7 @@ class NET_EXPORT NetworkChangeNotifier {
   // Implementations must be thread-safe. Implementations must also be
   // cheap as they are called often.
   virtual ConnectionType GetCurrentConnectionType() const = 0;
+  virtual ConnectionSubtype GetCurrentConnectionSubtype() const;
   virtual void GetCurrentMaxBandwidthAndConnectionType(
       double* max_bandwidth_mbps,
       ConnectionType* connection_type) const;