Add ResetModem method and call it once non_cellular activation is done.

chrome/browser/chromeos/cros/network_library.h

Index: chrome/browser/chromeos/cros/network_library.h
diff --git a/chrome/browser/chromeos/cros/network_library.h b/chrome/browser/chromeos/cros/network_library.h
index fe07b3c5b1e2aea9d8509c21109919722e7f42ac..f0c3b0b86863ae32d2825932311d403f936d93a7 100644
--- a/chrome/browser/chromeos/cros/network_library.h
+++ b/chrome/browser/chromeos/cros/network_library.h
@@ -1566,6 +1566,10 @@ class NetworkLibrary {
   virtual void SetCarrier(const std::string& carrier,
                           const NetworkOperationCallback& completed) = 0;
 
+  // Resets the cellular device, calls the closure once the transition is
+  // complete.
+  virtual void ResetModem() = 0;
+
   // Return true if GSM SIM card can work only with enabled roaming.
   virtual bool IsCellularAlwaysInRoaming() = 0;