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/update_manager/state_factory.cc b/update_manager/state_factory.cc
index 208ed51..7293692 100644
--- a/update_manager/state_factory.cc
+++ b/update_manager/state_factory.cc
@@ -46,7 +46,7 @@
 
 State* DefaultStateFactory(
     policy::PolicyProvider* policy_provider,
-    org::chromium::LibCrosServiceInterfaceProxyInterface* libcros_proxy,
+    org::chromium::KioskAppServiceInterfaceProxyInterface* kiosk_app_proxy,
     chromeos_update_engine::SystemState* system_state) {
   chromeos_update_engine::ClockInterface* const clock = system_state->clock();
   unique_ptr<RealConfigProvider> config_provider(
@@ -70,7 +70,7 @@
 #endif  // USE_SHILL
   unique_ptr<RealRandomProvider> random_provider(new RealRandomProvider());
   unique_ptr<RealSystemProvider> system_provider(new RealSystemProvider(
-      system_state->hardware(), system_state->boot_control(), libcros_proxy));
+      system_state->hardware(), system_state->boot_control(), kiosk_app_proxy));
 
   unique_ptr<RealTimeProvider> time_provider(new RealTimeProvider(clock));
   unique_ptr<RealUpdaterProvider> updater_provider(