Hook up ProximityAuthSystem in EasyUnlockService.

components/proximity_auth/messenger_impl.h

Index: components/proximity_auth/messenger_impl.h
diff --git a/components/proximity_auth/messenger_impl.h b/components/proximity_auth/messenger_impl.h
index a64c2aafb70c91e3babdc1aabcc41c7d6e95db09..88aac0b25546abb705a81cf2f17f71c93010393f 100644
--- a/components/proximity_auth/messenger_impl.h
+++ b/components/proximity_auth/messenger_impl.h
@@ -54,6 +54,7 @@ class MessengerImpl : public Messenger, public ConnectionObserver {
   struct PendingMessage {
     PendingMessage();
     PendingMessage(const base::DictionaryValue& message);
+    PendingMessage(const std::string& message);
     ~PendingMessage();
 
     // The message, serialized as JSON.
@@ -85,6 +86,10 @@ class MessengerImpl : public Messenger, public ConnectionObserver {
   // response.
   void HandleUnlockResponseMessage(const base::DictionaryValue& message);
 
+  // For iOS, we need to poll the phone every few seconds to keep the app alive
+  // in the background. This function starts the poll loop.
+  void PollScreenStateForIOS();
+
   // ConnectionObserver:
   void OnConnectionStatusChanged(Connection* connection,
                                  Connection::Status old_status,