[CrOS Tether] Create BleScanner, a class which scan BLE advertisements and identifies nearby device…

chromeos/components/tether/local_device_data_provider.h

Index: chromeos/components/tether/local_device_data_provider.h
diff --git a/chromeos/components/tether/local_device_data_provider.h b/chromeos/components/tether/local_device_data_provider.h
index 0d507cc3cfd1e450c70df3b64aa743a4a7cf3d38..4125049aaf53c703151d28b9a9598428cc5e6619 100644
--- a/chromeos/components/tether/local_device_data_provider.h
+++ b/chromeos/components/tether/local_device_data_provider.h
@@ -36,7 +36,7 @@ class LocalDeviceDataProvider {
   // Fetches the public key and/or the beacon seeds for the local device.
   // Returns whether the operation succeeded. If |nullptr| is passed as a
   // parameter, the associated data will not be fetched.
-  bool GetLocalDeviceData(
+  virtual bool GetLocalDeviceData(
       std::string* public_key_out,
       std::vector<cryptauth::BeaconSeed>* beacon_seeds_out) const;