Expose signing key from cloud policy stores

components/policy/core/common/cloud/user_cloud_policy_store_base.cc

Index: components/policy/core/common/cloud/user_cloud_policy_store_base.cc
diff --git a/components/policy/core/common/cloud/user_cloud_policy_store_base.cc b/components/policy/core/common/cloud/user_cloud_policy_store_base.cc
index 8c3b0e22a039bb2b67839423deb5ce6ae1089eb7..8df5f3c49ae45dfb047abf30cb63068e677dc297 100644
--- a/components/policy/core/common/cloud/user_cloud_policy_store_base.cc
+++ b/components/policy/core/common/cloud/user_cloud_policy_store_base.cc
@@ -45,11 +45,13 @@ UserCloudPolicyStoreBase::CreateValidator(
 
 void UserCloudPolicyStoreBase::InstallPolicy(
     std::unique_ptr<enterprise_management::PolicyData> policy_data,
-    std::unique_ptr<enterprise_management::CloudPolicySettings> payload) {
+    std::unique_ptr<enterprise_management::CloudPolicySettings> payload,
+    const std::string& public_key) {
   // Decode the payload.
   policy_map_.Clear();
   DecodePolicy(*payload, external_data_manager(), &policy_map_);
   policy_ = std::move(policy_data);
+  public_key_ = public_key;
 }
 
 }  // namespace policy