chromeos-config: Change white label model and signature format.

Change the config declaration scheme so all white labels will have model
name prefixed in the generated signature ID.

BUG=chromium:797567
TEST=(firmware) pack_firmware_functest.py
CQ-DEPEND=CL:858879

Change-Id: Ia2f3d6b3e10c9dbf7296b7c215f04824a7fd863a
Reviewed-on: https://chromium-review.googlesource.com/859405
Commit-Ready: Hung-Te Lin <hungte@chromium.org>
Tested-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-by: Nick Sanders <nsanders@chromium.org>
(cherry picked from commit 4de5e5212f4da7f439654b2623ea04ea5415f3ba)
Reviewed-on: https://chromium-review.googlesource.com/905903
Reviewed-by: YH Lin <yueherngl@chromium.org>
Reviewed-by: Patrick Berny <pberny@chromium.org>
Commit-Queue: Patrick Berny <pberny@chromium.org>
Tested-by: Patrick Berny <pberny@chromium.org>
Trybot-Ready: Patrick Berny <pberny@chromium.org>
diff --git a/chromeos-config/cros_config_host/libcros_config_host.py b/chromeos-config/cros_config_host/libcros_config_host.py
index 1318bc5..cdbb578 100644
--- a/chromeos-config/cros_config_host/libcros_config_host.py
+++ b/chromeos-config/cros_config_host/libcros_config_host.py
@@ -985,9 +985,10 @@
       if whitelabels:
         for whitelabel in whitelabels.subnodes.values():
           key_id = whitelabel.GetStr('key-id')
-          result[whitelabel.name] = info._replace(
-              model=whitelabel.name, key_id=key_id, have_image=False,
-              sig_id=whitelabel.name)
+          whitelabel_name = '%s-%s' % (base_model.name, whitelabel.name)
+          result[whitelabel_name] = info._replace(
+              model=whitelabel_name, key_id=key_id, have_image=False,
+              sig_id=whitelabel_name)
       return result
 
   class Property(object):