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Filter bad first-paint values. #9532

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merged 2 commits into from May 24, 2017
Merged

Filter bad first-paint values. #9532

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1b22a35
Filter bad first paint values.
cramforce May 24, 2017
e323e86
Fix test
cramforce May 24, 2017
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35 changes: 25 additions & 10 deletions src/service/performance-impl.js
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Expand Up @@ -164,16 +164,7 @@ export class Performance {

onload_() {
this.tick('ol');
// Detect deprecated first pain time API
// https://bugs.chromium.org/p/chromium/issues/detail?id=621512
// We'll use this until something better is available.
if (!this.win.PerformancePaintTiming
&& this.win.chrome
&& typeof this.win.chrome.loadTimes == 'function') {
this.tickDelta('fp',
this.win.chrome.loadTimes().firstPaintTime * 1000 -
this.win.performance.timing.navigationStart);
}
this.tickLegacyFirstPaintTime_();
}

/**
Expand All @@ -198,6 +189,30 @@ export class Performance {
observer.observe({entryTypes: ['paint']});
}

/**
* Tick fp time based on Chrome's legacy paint timing API when
* appropriate.
* `registerPaintTimingObserver_` calls the standards based API and this
* method does nothing if it is available.
*/
tickLegacyFirstPaintTime_() {
// Detect deprecated first pain time API
// https://bugs.chromium.org/p/chromium/issues/detail?id=621512
// We'll use this until something better is available.
if (!this.win.PerformancePaintTiming
&& this.win.chrome
&& typeof this.win.chrome.loadTimes == 'function') {
const fpTime = this.win.chrome.loadTimes().firstPaintTime
* 1000 - this.win.performance.timing.navigationStart;
if (fpTime <= 1) {
// Throw away bad data generated from an apparent Chrome bug
// that is fixed in later Chrome versions.
return;
}
this.tickDelta('fp', fpTime);
}
}

/**
* Measure the delay the user perceives of how long it takes
* to load the initial viewport.
Expand Down