Expose connection subtype from NetworkChangeNotifier

net/android/network_change_notifier_android.cc

 // 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.
 
 ////////////////////////////////////////////////////////////////////////////////
 // Threading considerations:
 //
 // This class is designed to meet various threading guarantees starting from the
 // ones imposed by NetworkChangeNotifier:
 // - The notifier can be constructed on any thread.
@@ skipping 142 matching lines @@
 
 NetworkChangeNotifierAndroid::~NetworkChangeNotifierAndroid() {
   delegate_->RemoveObserver(this);
 }
 
 NetworkChangeNotifier::ConnectionType
 NetworkChangeNotifierAndroid::GetCurrentConnectionType() const {
   return delegate_->GetCurrentConnectionType();
 }
 
+NetworkChangeNotifier::ConnectionSubtype
+NetworkChangeNotifierAndroid::GetCurrentConnectionSubtype() const {
+  return delegate_->GetCurrentConnectionSubtype();

[pauljensen, 2017/05/10 16:47:07]

Hmm this is a potential threading violation.  NCN::GetConnectionSubtype() is
advertised as thread-safe, but here we're implementing it by calling a function
that can only be called on the NCN's thread.  In Chrome this will be the UI
thread, in Cronet this will be an obscure initialization thread.

[tbansal1, 2017/05/11 01:08:52]

I will send a CL tomorrow to fix this. Thanks for noticing this.

+}
+
 void NetworkChangeNotifierAndroid::GetCurrentMaxBandwidthAndConnectionType(
     double* max_bandwidth_mbps,
     ConnectionType* connection_type) const {
   delegate_->GetCurrentMaxBandwidthAndConnectionType(max_bandwidth_mbps,
                                                      connection_type);
 }
 
 void NetworkChangeNotifierAndroid::ForceNetworkHandlesSupportedForTesting() {
   force_network_handles_supported_for_testing_ = true;
 }
@@ skipping 102 matching lines @@
       NetworkChangeNotifier::GetConnectionType();
   NetworkChangeNotifier::LogOperatorCodeHistogram(type);
   if (NetworkChangeNotifier::IsConnectionCellular(type)) {
     UMA_HISTOGRAM_ENUMERATION("NCN.CellularConnectionSubtype",
                               delegate_->GetCurrentConnectionSubtype(),
                               SUBTYPE_LAST + 1);
   }
 }
 
 }  // namespace net