<!--
Copyright 2023 The Chromium Authors
Use of this source code is governed by a BSD-style license that can be
found in the LICENSE file.

This file is used to generate a comprehensive list of Prefetch histograms
along with a detailed description for each histogram.

For best practices on writing histogram descriptions, see
https://chromium.googlesource.com/chromium/src.git/+/HEAD/tools/metrics/histograms/README.md

Please follow the instructions in the OWNERS file in this directory to find a
reviewer. If no OWNERS file exists, please consider signing up at
go/reviewing-metrics (Googlers only), as all subdirectories are expected to
have an OWNERS file. As a last resort you can send the CL to
chromium-metrics-reviews@google.com.
-->

<histogram-configuration>

<histograms>

<variants name="PreloadingPredictor">
  <variant name="BackButtonHover"
      summary="When the user hovers their mouse over the back button."/>
  <variant name="BackGestureNavigation"
      summary="When overscroll that could trigger a back navigation starts."/>
  <variant name="DefaultSearchEngine"
      summary="When preloading is triggered from the default search engine
               suggest service."/>
  <variant name="kLinkRel"
      summary="When preloading is triggered by the 'rel' keyword embedded in
               the link element."/>
  <variant name="kUnspecified" summary=""/>
  <variant name="kUrlPointerDownOnAnchor"
      summary="When preloading is triggered by OnPointerDown."/>
  <variant name="kUrlPointerHoverOnAnchor"
      summary="When preloading is triggered by OnPointerHover."/>
  <variant name="MouseBackButton"
      summary="When a mouse down of a mouse back button is seen."/>
  <variant name="OmniboxDirectURLInput"
      summary="When preloading is triggered from the Omnibox DUI."/>
  <variant name="OmniboxMousePredictor"
      summary="When preloading is triggered from the default search suggest
               due to mousedown on a Omnibox Search suggestion."/>
  <variant name="OmniboxSearchPredictor"
      summary="When preloading is triggered from the default search suggest
               due to change in Omnibox selection."/>
  <variant name="PointerDownOnAnchor"
      summary="When a pointerdown event happens on a HTTP/HTTPS anchor."/>
  <variant name="SpeculationRules"
      summary="When preloading is triggered by the speculation rules."/>
</variants>

<variants name="PreloadingType">
  <variant name="NoStatePrefetch" summary=""/>
  <variant name="Preconnect" summary=""/>
  <variant name="Prefetch" summary=""/>
  <variant name="Prerender" summary=""/>
  <variant name="Unspecified" summary=""/>
</variants>

<histogram name="Preloading.AnchorElementPreloader.PreloadingTriggered"
    enum="AnchorElementPreloaderType" expires_after="2023-10-08">
  <owner>spelchat@chromium.org</owner>
  <owner>curranmax@chromium.org</owner>
  <owner>chrome-brapp-loading@google.com</owner>
  <summary>
    Logged once for each preconnection request sent by renderer to the browser
    when intercepting pointerdown events. Note that the browser may ignore some
    of those requests (like duplicate requests or requests made by users that
    disabled preloading via the UI) and will not always forward the preconnect
    request to the network service. Associated with the Source ID of the page
    triggering the preconnection.
  </summary>
</histogram>

<histogram name="Preloading.Predictor.{PreloadingPredictor}.Precision"
    enum="PredictorConfusionMatrix" expires_after="2024-06-01">
  <owner>isaboori@google.com</owner>
  <owner>spelchat@chromium.org</owner>
  <owner>sreejakshetty@chromium.org</owner>
  <owner>jbroman@chromium.org</owner>
  <owner>chrome-brapp-loading@chromium.org</owner>
  <summary>
    After the user starts a new navigation, the outcome of the
    {PreloadingPredictor} preloading predictor is recorded as a true positive or
    a false positive. These statistics are used to compute precision of the
    preloading predictor. The statistics about negative cases are not required
    to compute the precision and are not recorded here.
  </summary>
  <token key="PreloadingPredictor" variants="PreloadingPredictor"/>
</histogram>

<histogram name="Preloading.Predictor.{PreloadingPredictor}.Recall"
    enum="PredictorConfusionMatrix" expires_after="2024-06-01">
  <owner>isaboori@google.com</owner>
  <owner>spelchat@chromium.org</owner>
  <owner>sreejakshetty@chromium.org</owner>
  <owner>jbroman@chromium.org</owner>
  <owner>chrome-brapp-loading@chromium.org</owner>
  <summary>
    After the user starts a new navigation, the outcome of any eligible
    {PreloadingPredictor} preloading predictor is recorded as a true positive or
    a false negative. These statistics are used to compute recall of the
    preloading predictor. The statistics about false positive and true negative
    cases are not required to compute the recall and are not recorded here.
  </summary>
  <token key="PreloadingPredictor" variants="PreloadingPredictor"/>
</histogram>

<histogram
    name="Preloading.PrerenderBackNavigationEligibility.{PreloadingPredictor}"
    enum="PrerenderBackNavigationEligibility" expires_after="2023-09-09">
  <owner>mcnee@chromium.org</owner>
  <owner>chrome-brapp-loading@chromium.org</owner>
  <summary>
    Records whether prerendering a back navigation is possible at the time of
    the prediction of a back navigation by {PreloadingPredictor}.
  </summary>
  <token key="PreloadingPredictor" variants="PreloadingPredictor"/>
</histogram>

<histogram
    name="Preloading.{PreloadingType}.Attempt.{PreloadingPredictor}.Precision"
    enum="PredictorConfusionMatrix" expires_after="2024-06-01">
  <owner>isaboori@google.com</owner>
  <owner>spelchat@chromium.org</owner>
  <owner>sreejakshetty@chromium.org</owner>
  <owner>jbroman@chromium.org</owner>
  <owner>chrome-brapp-loading@chromium.org</owner>
  <summary>
    After the user starts a new navigation, the outcome of the preloading
    attempt of type {PreloadingType} that is triggered by {PreloadingPredictor}
    is recorded as a true positive or a false positive. These statistics are
    used to compute precision of the preloading attempt. The statistics about
    negative cases are not required to compute the precision and are not
    recorded here.
  </summary>
  <token key="PreloadingType" variants="PreloadingType"/>
  <token key="PreloadingPredictor" variants="PreloadingPredictor"/>
</histogram>

<histogram
    name="Preloading.{PreloadingType}.Attempt.{PreloadingPredictor}.Recall"
    enum="PredictorConfusionMatrix" expires_after="2024-06-01">
  <owner>isaboori@google.com</owner>
  <owner>spelchat@chromium.org</owner>
  <owner>sreejakshetty@chromium.org</owner>
  <owner>jbroman@chromium.org</owner>
  <owner>chrome-brapp-loading@chromium.org</owner>
  <summary>
    After the user starts a new navigation, the outcome of any eligible
    preloading attempt of type {PreloadingType} that is triggered by
    {PreloadingPredictor} or the lack of an attempt by an eligible predictor is
    recorded as a true positive or a false negative. These statistics are used
    to compute recall of the preloading attempt. The statistics about false
    positive and true negative cases are not required to compute the recall and
    are not recorded here.
  </summary>
  <token key="PreloadingType" variants="PreloadingType"/>
  <token key="PreloadingPredictor" variants="PreloadingPredictor"/>
</histogram>

<histogram
    name="Preloading.{PreloadingType}.Attempt.{PreloadingPredictor}.TriggeringOutcome"
    enum="PreloadingTriggeringOutcome" expires_after="2024-06-01">
  <owner>spelchat@chromium.org</owner>
  <owner>sreejakshetty@chromium.org</owner>
  <owner>jbroman@chromium.org</owner>
  <owner>liuwilliam@chromium.org</owner>
  <owner>chrome-brapp-loading@chromium.org</owner>
  <summary>
    Records the triggering outcome of a preloading attempt of type
    {PreloadingType} and triggered by {PreloadingPredictor} that happened on the
    previous page load at the time a new navigation is started.
  </summary>
  <token key="PreloadingType" variants="PreloadingType"/>
  <token key="PreloadingPredictor" variants="PreloadingPredictor"/>
</histogram>

</histograms>

</histogram-configuration>