Expose signing key from cloud policy stores

chrome/browser/chromeos/policy/device_cloud_policy_store_chromeos.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/chromeos/policy/device_cloud_policy_store_chromeos.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/logging.h"
@@ skipping 146 matching lines @@
     if (policy_data)
       policy_->MergeFrom(*policy_data);
 
     PolicyMap new_policy_map;
     if (is_managed()) {
       DecodeDevicePolicy(*device_settings_service_->device_settings(),
                          &new_policy_map);
     }
     policy_map_.Swap(&new_policy_map);
 
+    scoped_refptr<ownership::PublicKey> key =
+        device_settings_service_->GetPublicKey();
+    policy_signature_public_key_ = key ? key->as_string() : std::string();
+
     NotifyStoreLoaded();
     return;
   }
   NotifyStoreError();
 }
 
 void DeviceCloudPolicyStoreChromeOS::UpdateStatusFromService() {
   switch (device_settings_service_->status()) {
     case chromeos::DeviceSettingsService::STORE_SUCCESS:
       status_ = STATUS_OK;
@@ skipping 53 matching lines @@
     UMA_HISTOGRAM_BOOLEAN(kDMTokenCheckHistogram, true);
   } else {
     LOG(ERROR) << "Device policy read on enrolled device yields "
                << "no DM token! Status: " << service_status << ".";
     chromeos::StartupUtils::MarkEnrollmentRecoveryRequired();
     UMA_HISTOGRAM_BOOLEAN(kDMTokenCheckHistogram, false);
   }
 }
 
 }  // namespace policy