Add support for Device.ProposeScan to NetworkDeviceHandler.

chromeos/network/network_device_handler.h

Index: chromeos/network/network_device_handler.h
diff --git a/chromeos/network/network_device_handler.h b/chromeos/network/network_device_handler.h
index 851f1f9b6a11f5ba218d5378bd3e3ebd54d1d2ab..fb921d172bc22b34741173b483a3f0893950ae59 100644
--- a/chromeos/network/network_device_handler.h
+++ b/chromeos/network/network_device_handler.h
@@ -61,6 +61,21 @@ class CHROMEOS_EXPORT NetworkDeviceHandler
       const base::Closure& callback,
       const network_handler::ErrorCallback& error_callback);
 
+  // Requests a network scan on the device specified by |device_path|.
+  // For cellular networks, the result of this call gets asynchronously stored
+  // in the corresponding DeviceState object through a property update. For all
+  // other technologies a service gets created for each found network, which
+  // can be accessed through the corresponding NetworkState object.
+  //
+  // TODO(armansito): Device.ProposeScan is deprecated and the preferred method
+  // of requesting a network scan is Manager.RequestScan, however shill
+  // currently doesn't support cellular network scans via Manager.RequestScan.
+  // Remove this method once shill supports it (crbug.com/262356).
+  void ProposeScan(
+      const std::string& device_path,
+      const base::Closure& callback,
+      const network_handler::ErrorCallback& error_callback);
+
   // Tells the device to set the modem carrier firmware, as specified by
   // |carrier|.
   //