Debugging mobile perf tests

[Philip Rogers]

Hi Kevin,

I cc'd the public paint-dev list so we have this written down somewhere.

To investigate a regression on system_health.common_mobile / browse:search:amp:2018 (link), we can force it to run on desktop. Edit "tools/perf/page_sets/system_health/browsing_stories.py" and change "SUPPORTED_PLATFORMS" to "platforms.DESKTOP_ONLY". Edit "tools/perf/benchmarks/system_health.py" and change "MobileCommonSystemHealth" to:

  PLATFORM = 'desktop'
  SUPPORTED_PLATFORM_TAGS = [platforms.DESKTOP]
  SUPPORTED_PLATFORMS = [story.expectations.ALL_DESKTOP]

With these changes, you can run the benchmark with:

./tools/perf/run_benchmark system_health.common_mobile --story="browse:search:amp:2018" --browser=system

If you would like to debug the page a bit, edit "tools/perf/page_sets/system_health/browsing_stories.py" and change the wait() in _DidLoadDocument from 2 to 99999. This will cause the benchmark to wait a very long time, so you can debug the page. You can also add --pause="before-run-story" if you want the browser to wait for you to open the inspector.

I found this page does have a background color animation:

animation: i-amphtml-loader-dots 2s infinite

@keyframes i-amphtml-loader-dots {
    0%,to {
        -webkit-transform: scale(.7);
        transform: scale(.7);
        background-color: rgba(0,0,0,0.3)
    }

    50% {
        -webkit-transform: scale(.8);
        transform: scale(.8);
        background-color: rgba(0,0,0,0.5)
    }
}