window.h5vcc.system.getAdvertisingId(); works

[zhongqiliang]

// compile cobalt/build/gn.py -p linux-x64x11 -C devel &&
autoninja -C out/linux-x64x11_devel blink_wpt_tests &&
autoninja -C out/linux-x64x11_devel dump_syms &&
autoninja -C out/linux-x64x11_devel minidump_stackwalk &&
autoninja -C out/linux-x64x11_devel cobalt/browser/h5vcc_system/public/mojom:mojom_js

// run third_party/blink/tools/run_web_tests.py -t linux-x64x11_devel wpt_internal/h5vcc/h5vcc-system

Commands for debugging: // remove historical test results rm -rf out/linux-x64x11_devel/layout-test-results*

// print call outputs for the test results. cat out/linux-x64x11_devel/layout-test-results/external/wpt/cobalt/h5vcc-system/*