Add UMA histograms for time between policy fetches

components/policy/core/common/cloud/cloud_policy_client.h

Index: components/policy/core/common/cloud/cloud_policy_client.h
diff --git a/components/policy/core/common/cloud/cloud_policy_client.h b/components/policy/core/common/cloud/cloud_policy_client.h
index 1f4f6efd9c94364d1e72da709a128198fa4aaa04..1e47306485d038da44e18a343843cb8aa09b67bf 100644
--- a/components/policy/core/common/cloud/cloud_policy_client.h
+++ b/components/policy/core/common/cloud/cloud_policy_client.h
@@ -221,6 +221,8 @@ class POLICY_EXPORT CloudPolicyClient {
     last_policy_timestamp_ = timestamp;
   }
 
+  const base::Time& last_policy_timestamp() { return last_policy_timestamp_; }
+
   void set_public_key_version(int public_key_version) {
     public_key_version_ = public_key_version;
     public_key_version_valid_ = true;