[EasyUnlock] Update ProximityMonitor to only check for RSSI proximity.

components/proximity_auth/messenger.h

Index: components/proximity_auth/messenger.h
diff --git a/components/proximity_auth/messenger.h b/components/proximity_auth/messenger.h
index d88f7d887fb9b458d27eb409b08e885879977365..7267982632973486b8e2283070cedaca3ac23909 100644
--- a/components/proximity_auth/messenger.h
+++ b/components/proximity_auth/messenger.h
@@ -42,6 +42,11 @@ class Messenger {
   // Returns the SecureContext instance used by the messenger. Ownership of the
   // SecureContext is not passed.
   virtual cryptauth::SecureContext* GetSecureContext() const = 0;
+
+  // Returns the underlying raw connection. Note that you should use
+  // |GetSecureContext()| instead if you want to send and receive messages
+  // securely.
+  virtual cryptauth::Connection* GetConnection() const = 0;
 };
 
 }  // namespace proximity_auth