cros_healthd: Update sku_number in cros_healthd_probe.mojom

Update cros_healthd_probe.mojom to keep it in sync with the copy in
Chrome OS.

Bug: 1026848
Test: DeviceStatusCollectorTest.TestCrosHealthdInfo
Change-Id: I7b35f6668f0f2627976c57f7a02cc22efeddbfd5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2013467Reviewed-by: Sergey Poromov <poromov@chromium.org>
Reviewed-by: Jack Rosenthal <jrosenth@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Jesse Schettler <jschettler@chromium.org>
Cr-Commit-Position: refs/heads/master@{#734226}

chrome/browser/chromeos/policy/status_collector/device_status_collector.cc

@@ -770,10 +770,10 @@ class DeviceStatusCollectorState : public StatusCollectorState {
       }
     }
     const auto& vpd_info = probe_result->vpd_info;
-    if (!vpd_info.is_null()) {
+    if (!vpd_info.is_null() && vpd_info->sku_number.has_value()) {
       em::SystemStatus* const system_status_out =
           response_params_.device_status->mutable_system_status();
-      system_status_out->set_vpd_sku_number(vpd_info->sku_number);
+      system_status_out->set_vpd_sku_number(vpd_info->sku_number.value());
     }
     const auto& battery_info = probe_result->battery_info;
     if (!battery_info.is_null()) {

chromeos/services/cros_healthd/public/mojom/cros_healthd_probe.mojom

@@ -74,8 +74,8 @@ struct NonRemovableBlockDeviceInfo {
 
 // Cached VPD read from sysfs.
 struct CachedVpdInfo {
-  // Contents of /sys/firmware/vpd/ro/sku_number.
-  string sku_number;
+  // Contents of /sys/firmware/vpd/ro/sku_number, if the device supports it.
+  string? sku_number;
 };
 
 // Information related to a device's CPU.