Adding pref to store the user-selected proximity threshold.

components/proximity_auth/unlock_manager_impl.h

Index: components/proximity_auth/unlock_manager_impl.h
diff --git a/components/proximity_auth/unlock_manager_impl.h b/components/proximity_auth/unlock_manager_impl.h
index c880844c0c3684f0ed863f4dd81d608fc5da3b2b..95bf32739a267f5f577a69c0e6db333ef9fa2a88 100644
--- a/components/proximity_auth/unlock_manager_impl.h
+++ b/components/proximity_auth/unlock_manager_impl.h
@@ -23,6 +23,8 @@
 #include "chromeos/dbus/power_manager_client.h"
 #endif
 
+class PrefService;
+
 namespace proximity_auth {
 
 class Messenger;
@@ -56,7 +58,8 @@ class UnlockManagerImpl : public UnlockManager,
   // Creates a ProximityMonitor instance for the given |connection|.
   // Exposed for testing.
   virtual std::unique_ptr<ProximityMonitor> CreateProximityMonitor(
-      cryptauth::Connection* connection);
+      cryptauth::Connection* connection,
+      PrefService* pref_service);
 
  private:
   // The possible lock screen states for the remote device.