update_engine: Use org.chromium.KioskAppService service.

Make update_engine use the org.chromium.KioskAppService
D-Bus service exported by Chrome rather than the old methods
under org.chromium.LibCrosService.

BUG=chromium:703229
TEST=unit tests pass; also hacked up RealSystemProvider to
     call its GetKioskAppRequiredPlatformVersion and
     manually verified that the D-Bus call succeeds

Change-Id: I02d503da1e1aec2319c75e2237c87bfcdcd1f7e5
Reviewed-on: https://chromium-review.googlesource.com/987325
Commit-Ready: Dan Erat <derat@chromium.org>
Tested-by: Dan Erat <derat@chromium.org>
Reviewed-by: Amin Hassani <ahassani@chromium.org>
diff --git a/real_system_state.h b/real_system_state.h
index 49f7c31..f1cd38f 100644
--- a/real_system_state.h
+++ b/real_system_state.h
@@ -25,7 +25,7 @@
 #include <policy/device_policy.h>
 
 #if USE_CHROME_KIOSK_APP
-#include <libcros/dbus-proxies.h>
+#include <kiosk-app/dbus-proxies.h>
 #endif  // USE_CHROME_KIOSK_APP
 
 #include "update_engine/certificate_checker.h"
@@ -129,7 +129,8 @@
  private:
   // Real DBus proxies using the DBus connection.
 #if USE_CHROME_KIOSK_APP
-  std::unique_ptr<org::chromium::LibCrosServiceInterfaceProxy> libcros_proxy_;
+  std::unique_ptr<org::chromium::KioskAppServiceInterfaceProxy>
+      kiosk_app_proxy_;
 #endif  // USE_CHROME_KIOSK_APP
 
   // Interface for the power manager.