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/real_system_provider.cc b/update_manager/real_system_provider.cc
index fdf7e86..53e9ab3 100644
--- a/update_manager/real_system_provider.cc
+++ b/update_manager/real_system_provider.cc
@@ -21,7 +21,7 @@
 #include <base/logging.h>
 #include <base/time/time.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/common/utils.h"
@@ -126,8 +126,8 @@
     string* required_platform_version) {
 #if USE_CHROME_KIOSK_APP
   brillo::ErrorPtr error;
-  if (!libcros_proxy_->GetKioskAppRequiredPlatformVersion(
-          required_platform_version, &error)) {
+  if (!kiosk_app_proxy_->GetRequiredPlatformVersion(required_platform_version,
+                                                    &error)) {
     LOG(WARNING) << "Failed to get kiosk required platform version";
     required_platform_version->clear();
     return false;