chromium/components/page_load_metrics/browser/observers/back_forward_cache_page_load_metrics_observer.cc

// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "components/page_load_metrics/browser/observers/back_forward_cache_page_load_metrics_observer.h"

#include "base/metrics/histogram_functions.h"
#include "base/time/default_tick_clock.h"
#include "base/time/time.h"
#include "components/page_load_metrics/browser/observers/core/uma_page_load_metrics_observer.h"
#include "components/page_load_metrics/browser/page_load_metrics_util.h"
#include "components/page_load_metrics/browser/responsiveness_metrics_normalization.h"
#include "components/page_load_metrics/common/page_visit_final_status.h"
#include "content/public/browser/navigation_handle.h"
#include "content/public/browser/web_contents.h"
#include "services/metrics/public/cpp/metrics_utils.h"
#include "services/metrics/public/cpp/ukm_builders.h"
#include "third_party/blink/public/common/features.h"

PageVisitFinalStatus;

namespace internal {

const char kHistogramFirstPaintAfterBackForwardCacheRestore[] = …;
const char kHistogramFirstRequestAnimationFrameAfterBackForwardCacheRestore[] = …;
const char kHistogramSecondRequestAnimationFrameAfterBackForwardCacheRestore[] = …;
const char kHistogramThirdRequestAnimationFrameAfterBackForwardCacheRestore[] = …;
const char kHistogramFirstInputDelayAfterBackForwardCacheRestore[] = …;
extern const char
    kHistogramCumulativeShiftScoreMainFrameAfterBackForwardCacheRestore[] = …;
extern const char kHistogramCumulativeShiftScoreAfterBackForwardCacheRestore[] = …;

const char kNumInteractions_AfterBackForwardCacheRestore[] = …;
const char
    kUserInteractionLatencyHighPercentile2_MaxEventDuration_AfterBackForwardCacheRestore
        [] = …;
const char
    kWorstUserInteractionLatency_MaxEventDuration_AfterBackForwardCacheRestore
        [] = …;

// Enables to emit zero values for some key metrics when back-forward cache is
// used.
//
// With this flag disabled, no samples are emitted for regular VOLT metrics
// after the page is restored from the back-forward cache. This means that we
// will miss a lot of metrics for history navigations after we launch back-
// forward cache. As metrics for history navigations tend to be better figures
// than other navigations (e.g., due to network cache), the average of such
// metrics values will become worse and might seem regression if we don't take
// any actions.
//
// To mitigate this issue, we plan to emit 0 samples for such key metrics for
// back-forward navigations. This is implemented behind this flag so far, and we
// will enable this by default when we reach the conclusion how to adjust them.
//
// For cumulative layout shift scores, we use actual score values for back-
// forward cache navigations instead of 0s.
BASE_FEATURE(…);

}  // namespace internal

BackForwardCachePageLoadMetricsObserver::
    BackForwardCachePageLoadMetricsObserver() = default;

BackForwardCachePageLoadMetricsObserver::
    ~BackForwardCachePageLoadMetricsObserver() { … }

page_load_metrics::PageLoadMetricsObserver::ObservePolicy
BackForwardCachePageLoadMetricsObserver::OnStart(
    content::NavigationHandle* navigation_handle,
    const GURL& currently_committed_url,
    bool started_in_foreground) { … }

page_load_metrics::PageLoadMetricsObserver::ObservePolicy
BackForwardCachePageLoadMetricsObserver::OnFencedFramesStart(
    content::NavigationHandle* navigation_handle,
    const GURL& currently_committed_url) { … }

page_load_metrics::PageLoadMetricsObserver::ObservePolicy
BackForwardCachePageLoadMetricsObserver::OnPrerenderStart(
    content::NavigationHandle* navigation_handle,
    const GURL& currently_committed_url) { … }

page_load_metrics::PageLoadMetricsObserver::ObservePolicy
BackForwardCachePageLoadMetricsObserver::OnHidden(
    const page_load_metrics::mojom::PageLoadTiming& timing) { … }

page_load_metrics::PageLoadMetricsObserver::ObservePolicy
BackForwardCachePageLoadMetricsObserver::OnEnterBackForwardCache(
    const page_load_metrics::mojom::PageLoadTiming& timing) { … }

void BackForwardCachePageLoadMetricsObserver::OnRestoreFromBackForwardCache(
    const page_load_metrics::mojom::PageLoadTiming& timing,
    content::NavigationHandle* navigation_handle) { … }

page_load_metrics::PageLoadMetricsObserver::ObservePolicy
BackForwardCachePageLoadMetricsObserver::ShouldObserveMimeType(
    const std::string& mime_type) const { … }

void BackForwardCachePageLoadMetricsObserver::
    OnFirstPaintAfterBackForwardCacheRestoreInPage(
        const page_load_metrics::mojom::BackForwardCacheTiming& timing,
        size_t index) { … }

void BackForwardCachePageLoadMetricsObserver::
    OnRequestAnimationFramesAfterBackForwardCacheRestoreInPage(
        const page_load_metrics::mojom::BackForwardCacheTiming& timing,
        size_t index) { … }

void BackForwardCachePageLoadMetricsObserver::
    OnFirstInputAfterBackForwardCacheRestoreInPage(
        const page_load_metrics::mojom::BackForwardCacheTiming& timing,
        size_t index) { … }

page_load_metrics::PageLoadMetricsObserver::ObservePolicy
BackForwardCachePageLoadMetricsObserver::FlushMetricsOnAppEnterBackground(
    const page_load_metrics::mojom::PageLoadTiming& timing) { … }

void BackForwardCachePageLoadMetricsObserver::OnComplete(
    const page_load_metrics::mojom::PageLoadTiming& timing) { … }

void BackForwardCachePageLoadMetricsObserver::RecordMetricsOnPageVisitEnd(
    const page_load_metrics::mojom::PageLoadTiming& timing,
    bool app_entering_background) { … }

void BackForwardCachePageLoadMetricsObserver::
    MaybeRecordNormalizedResponsivenessMetrics() { … }

void BackForwardCachePageLoadMetricsObserver::
    MaybeRecordLayoutShiftScoreAfterBackForwardCacheRestore(
        const page_load_metrics::mojom::PageLoadTiming& timing) { … }

void BackForwardCachePageLoadMetricsObserver::
    MaybeRecordPageEndAfterBackForwardCacheRestore(
        bool app_entering_background) { … }

void BackForwardCachePageLoadMetricsObserver::
    MaybeRecordForegroundDurationAfterBackForwardCacheRestore(
        const base::TickClock* clock,
        bool app_entering_background) const { … }

int64_t BackForwardCachePageLoadMetricsObserver::
    GetUkmSourceIdForBackForwardCacheRestore(size_t index) const { … }

int64_t BackForwardCachePageLoadMetricsObserver::
    GetLastUkmSourceIdForBackForwardCacheRestore() const { … }