Add PLT measurement to Resource Prefetching for Mobile Web

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 6446d031a849225eadfe9606352758f9ef6b108a..b245d88a1cad957b036d12f9cfb64503b8edf10a 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -27673,6 +27673,502 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="ResourcePrefetchPredictor.DbStringTooLong">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    A boolean that used to indicate a corner case when certain resources are not
+    written to the Predictor database becuase their URLs are too long. We
+    monitor this number to ensure that we do not discard too many resources.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.HavePrefetchResults">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    A boolean that used to indicate a corner case when we may not have prefetch
+    results even though prefetching is enabled and predictions are present,
+    because another navigation in the same tab canceled the prefetching of the
+    previous load.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.HistoryVisitCountForUrl">

[Alexei Svitkine (slow), 2014/10/20 18:30:36]

I don't see this in your CL (as well as many of the other histogram descriptions
you're adding), what's the story here?

[Zhen Wang, 2014/10/27 14:12:47]

This resource prefetch feature was originally part of Chromium, but later was
removed because the original author does not continue to maintain it and gather
experiment data. We found this feature may be beneficial to mobile devices and
brought the code back in CL 462423004.

There were UMA recording code inside the original code. But since the purpose of
CL 462423004 was to make the old code compile and work with current system, we
didn't update histograms.xml.

Now we have verified the old UMA recording and add some new ones for PLT; and
update histograms.xml all together.

See:
https://codereview.chromium.org/462423004/
https://codereview.chromium.org/576313002/ (fix mem leak in 462423004)

[Alexei Svitkine (slow), 2014/10/29 16:49:52]

It seems these other histograms are actually listed in the internal (non-open
source) version of histograms.xml:

http://cs/ResourcePrefetchPredictor.HistoryVisitCountForUrl

I agree we should move them over to the open source version of the file and set
owners for them. But that should be done in a separate CL, not as part of this
CL which is changing other code.

[Zhen Wang, 2014/10/29 17:35:26]

I see. I will prepare another CL to do the movement for the internal ones.

+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    The visit count of a URL in the history database, measured when the onload
+    fires for the URL. Helpful in figuring out how what visit count should be
+    used to start learning about a URL.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.Host.PredictedPrefetchCount">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    Assuming a fixed number of URLs could be prefetched max, how many would be
+    available for prefetch (after we apply our heuristics for picking
+    subresources to prefetch for a navigation).
+
+    This stat is recorded when the predictor uses the host of the main frame url
+    as the key for prediction.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.Host.PredictedPrefetchFromCache">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    When we have predictions for a navigation, we measure the accuracy of the
+    predictions against the actual resources downloaded. This histogram gives
+    the distribution of the predictions that were fetched by the page and served
+    from the cache restricted to some max predictions.
+
+    This stat is recorded when the predictor uses the host of the main frame url
+    as the key for prediction.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.Host.PredictedPrefetchFromNetwork">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    When we have predictions for a navigation, we measure the accuracy of the
+    predictions against the actual resources downloaded. This histogram gives
+    the distribution of the predictions that were fetched by the page and served
+    from the network restricted to some max predictions.
+
+    This stat is recorded when the predictor uses the host of the main frame url
+    as the key for prediction.
+  </summary>
+</histogram>
+
+<histogram
+    name="ResourcePrefetchPredictor.Host.PredictedPrefetchFromNetworkPercentOfTotalFromNetwork">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    Similar to ResourcePrefetchPredictor.Host.PredictedPrefetchFromNetwork but
+    as a percent of the total number of resources the page actually fetched from
+    the network. This depcits the major gains that we can get.
+
+    This stat is recorded when the predictor uses the host of the main frame url
+    as the key for prediction.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.Host.PredictedPrefetchMisses">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    When we have predictions for a navigation, we measure the accuracy of the
+    predictions against the actual resources downloaded. This histogram gives
+    the distribution of the predictions that were fetched by the page not used
+    by the page, restricted to some max predictions.
+
+    This stat is recorded when the predictor uses the host of the main frame url
+    as the key for prediction.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.Host.PrefetchCancelled">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    For prefetching based on host of main frame URL, the percentage of
+    prefetches cancelled as a percentage of the total number of resources that
+    the predictor tried to prefetch.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.Host.PrefetchFailed">
+  <summary>
+    For prefetching based on host of main frame URL, the percentage of
+    prefetches failed as a percentage of the total number of resources that the
+    predictor tried to prefetch.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.Host.PrefetchFromCacheNotUsed">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    For prefetching based on host of main frame URL, the percentage of
+    successful prefetches that came from cache while prefetching but were not
+    requested by the page, as a percentage of the total number of resources that
+    the predictor tried to prefetch.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.Host.PrefetchFromCacheUsedFromCache">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    For prefetching based on host of main frame URL, the percentage of
+    successful prefetches that came from cache while prefetching and also came
+    from the cache when the page requested it, as a percentage of the total
+    number of resources that the predictor tried to prefetch.
+  </summary>
+</histogram>
+
+<histogram
+    name="ResourcePrefetchPredictor.Host.PrefetchFromCacheUsedFromNetwork">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    For prefetching based on host of main frame URL, the percentage of
+    successful prefetches that came from cache while prefetching but came from
+    the network when the page requested it, as a percentage of the total number
+    of resources that the predictor tried to prefetch.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.Host.PrefetchFromNetworkNotUsed">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    For prefetching based on host of main frame URL, the percentage of
+    successful prefetches that came from network while prefetching but were not
+    requested by the page, as a percentage of the total number of resources that
+    the predictor tried to prefetch.
+  </summary>
+</histogram>
+
+<histogram
+    name="ResourcePrefetchPredictor.Host.PrefetchFromNetworkUsedFromCache">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    For prefetching based on host of main frame URL, the percentage of
+    successful prefetches that came from network while prefetching but came from
+    the cache when the page requested it, as a percentage of the total number of
+    resources that the predictor tried to prefetch.
+  </summary>
+</histogram>
+
+<histogram
+    name="ResourcePrefetchPredictor.Host.PrefetchFromNetworkUsedFromNetwork">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    For prefetching based on host of main frame URL, the percentage of
+    successful prefetches that came from cache while prefetching and also came
+    from the network when the page requested it, as a percentage of the total
+    number of resources that the predictor tried to prefetch.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.Host.PrefetchNotStarted">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    For prefetching based on host of main frame URL, the percentage of resources
+    that were prefetchable but were not prefetched as a percentage of
+    prefetchable resources.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.HostTableHostCount">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    The count of number of unique hosts in the HostTable, i.e. the number of
+    hosts that the database has prediction data for. This data is useful for
+    determining the recall/precision as a function of the number of hosts that
+    need to be tracked by the database. Measured at startup.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.HostTableRowCount">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    The count of number of rows in the HostTable. This is effecively the number
+    of (host, resource URL) pairs in the database. This is measured at startup
+    and used to get an estimate of the data size.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.MainFrameRequestStats"
+    enum="ResourcePrefetchPredictorMainFrameRequestStats">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    Records stats about main frame navigations. Records the total number of
+    requests/responses/redirects for main frame urls along with the numbers for
+    how often the predictor can process such events. This is useful to figure
+    out what percentange of requests are handled by the predictor and also for
+    sanity checking the other stats.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.NavigationEvent"
+    enum="ResourcePrefetchPredictorNavigationEvent">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    Records stats about various interesting events such as - request start,
+    response start, redirect, onload, etc during the load of a main frame.
+    Essential for understanding the complete life of a navigation request start
+    to the onload fire and the events that occur in between.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.PageNotPrefetchedNetworkType"
+    enum="ResourcePrefetchPredictorPageNotPrefetchedNetworkType">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    Records the number of non-prefetched pages on each type of network.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.PagePrefetchedNetworkType"
+    enum="ResourcePrefetchPredictorPagePrefetchedNetworkType">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    Records the number of prefetched pages on each type of network.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.PLT" units="milliseconds">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    Page load time. It starts from when the main frame URL request is sent out
+    to when the main frame document load is completed.
+
+    This is recorded for both prefetched and non-prefetched pages.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.PLT.PageNotPrefetched"
+    units="milliseconds">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    Page load time. It starts from when the main frame URL request is sent out
+    to when the main frame document load is completed.
+
+    This is recorded for non-prefetched pages.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.PLT.PagePrefetched"
+    units="milliseconds">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    Page load time. It starts from when the main frame URL request is sent out
+    to when the main frame document load is completed.
+
+    This is recorded for prefetched pages.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.PLT.PagePrefetched.Host"
+    units="milliseconds">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    Page load time. It starts from when the main frame URL request is sent out
+    to when the main frame document load is completed.
+
+    This is recorded for pages prefetched based on the host of main frame URL.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.PLT.PagePrefetched.Url"
+    units="milliseconds">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    Page load time. It starts from when the main frame URL request is sent out
+    to when the main frame document load is completed.
+
+    This is recorded for pages prefetched based on main frame URL.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.ReportingEvent"
+    enum="ResourcePrefetchPredictorReportingEvent">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    Records stats about various interesting events such as - when partial or all
+    of history is cleared. It will include events which do not necessarily
+    happen during a navigation (which are reported in
+    ResourcePrefetchPredictor.NavigationEvent).
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.RequestStats"
+    enum="ResourcePrefetchPredictorRequestStats">
+  <summary>
+    Records stats about requests, redirects, and responses observed by the
+    ResourcePrefetchPredictorObserver. These stats are useful as a baseline for
+    other stats.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.ResourceStatus"
+    enum="ResourcePrefetchPredictorResourceStatus">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    The distribution of the reasons for which subresources are ignored during
+    prefetching. This helps us prioritze reasons we should further investigate
+    to increase coverage. This is reported as a bit map and every status will be
+    a bitwise or of the underlying reasons.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.Url.PredictedPrefetchCount">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    Assuming a fixed number of URLs could be prefetched max, how many would be
+    available for prefetch (after we apply our heuristics for picking
+    subresources to prefetch for a navigation).
+
+    This stat is recorded when the predictor uses the main frame url as the key
+    for prediction.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.Url.PredictedPrefetchFromCache">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    When we have predictions for a navigation, we measure the accuracy of the
+    predictions against the actual resources downloaded. This histogram gives
+    the distribution of the predictions that were fetched by the page and served
+    from the cache restricted to some max predictions.
+
+    This stat is recorded when the predictor uses the main frame url as the key
+    for prediction.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.Url.PredictedPrefetchFromNetwork">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    When we have predictions for a navigation, we measure the accuracy of the
+    predictions against the actual resources downloaded. This histogram gives
+    the distribution of the predictions that were fetched by the page and served
+    from the network restricted to some max predictions.
+
+    This stat is recorded when the predictor uses the main frame url as the key
+    for prediction.
+  </summary>
+</histogram>
+
+<histogram
+    name="ResourcePrefetchPredictor.Url.PredictedPrefetchFromNetworkPercentOfTotalFromNetwork">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    Similar to ResourcePrefetchPredictor.Url.PredictedPrefetchFromNetwork but as
+    a percent of the total number of resources the page actually fetched from
+    the network. This depcits the major gains that we can get.
+
+    This stat is recorded when the predictor uses the main frame url as the key
+    for prediction.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.Url.PredictedPrefetchMisses">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    When we have predictions for a navigation, we measure the accuracy of the
+    predictions against the actual resources downloaded. This histogram gives
+    the distribution of the predictions that were fetched by the page not used
+    by the page, restricted to some max predictions.
+
+    This stat is recorded when the predictor uses the main frame url as the key
+    for prediction.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.Url.PrefetchCancelled">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    For prefetching based on the main frame URL, the percentage of prefetches
+    cancelled as a percentage of the total number of resources that the
+    predictor tried to prefetch.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.Url.PrefetchFailed">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    For prefetching based on the main frame URL, the percentage of prefetches
+    failed as a percentage of the total number of resources that the predictor
+    tried to prefetch.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.Url.PrefetchFromCacheNotUsed">
+  <summary>
+    For prefetching based on the main frame URL, the percentage of successful
+    prefetches that came from cache while prefetching but were not requested by
+    the page, as a percentage of the total number of resources that the
+    predictor tried to prefetch.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.Url.PrefetchFromCacheUsedFromCache">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    For prefetching based on the main frame URL, the percentage of successful
+    prefetches that came from cache while prefetching and also came from the
+    cache when the page requested it, as a percentage of the total number of
+    resources that the predictor tried to prefetch.
+  </summary>
+</histogram>
+
+<histogram
+    name="ResourcePrefetchPredictor.Url.PrefetchFromCacheUsedFromNetwork">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    For prefetching based on the main frame URL, the percentage of successful
+    prefetches that came from cache while prefetching but came from the network
+    when the page requested it, as a percentage of the total number of resources
+    that the predictor tried to prefetch.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.Url.PrefetchFromNetworkNotUsed">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    For prefetching based on the main frame URL, the percentage of successful
+    prefetches that came from network while prefetching but were not requested
+    by the page, as a percentage of the total number of resources that the
+    predictor tried to prefetch.
+  </summary>
+</histogram>
+
+<histogram
+    name="ResourcePrefetchPredictor.Url.PrefetchFromNetworkUsedFromCache">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    For prefetching based on the main frame URL, the percentage of successful
+    prefetches that came from network while prefetching but came from the cache
+    when the page requested it, as a percentage of the total number of resources
+    that the predictor tried to prefetch.
+  </summary>
+</histogram>
+
+<histogram
+    name="ResourcePrefetchPredictor.Url.PrefetchFromNetworkUsedFromNetwork">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    For prefetching based on the main frame URL, the percentage of successful
+    prefetches that came from cache while prefetching and also came from the
+    network when the page requested it, as a percentage of the total number of
+    resources that the predictor tried to prefetch.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.Url.PrefetchNotStarted">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    For prefetching based on host of main frame URL, the percentage of resources
+    that were prefetchable but were not prefetched as a percentage of
+    prefetchable resources.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.UrlTableMainFrameUrlCount">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    The count of number of unique main frame urls in the UrlTable, i.e. the
+    number of webpages that the database has prediction data for. This data is
+    useful for determining the recall/precision as a function of the number of
+    webpages that need to be tracked by the database. Measured at startup.
+  </summary>
+</histogram>
+
+<histogram name="ResourcePrefetchPredictor.UrlTableRowCount">
+  <owner>zhenw@chromium.org</owner>
+  <summary>
+    The count of number of rows in the UrlTable. This is effecively the number
+    of (main frame URL, resource URL) pairs in the database. This is measured at
+    startup and used to get an estimate of the data size.
+  </summary>
+</histogram>
+
 <histogram name="SafeBrowsing.EnabledSettingChanged" enum="BooleanEnabled">
   <owner>feng@chromium.org</owner>
   <summary>
@@ -50660,6 +51156,83 @@ To add a new entry, add it with any value and run test to compute valid value.
   <int value="1" label="Has client"/>
 </enum>
 
+<enum name="ResourcePrefetchPredictorMainFrameRequestStats" type="int">
+  <int value="0" label="MAIN_FRAME_REQUEST_STATS_TOTAL_REQUESTS"/>
+  <int value="1" label="MAIN_FRAME_REQUEST_STATS_PROCESSED_REQUESTS"/>
+  <int value="2" label="MAIN_FRAME_REQUEST_STATS_TOTAL_REDIRECTS"/>
+  <int value="3" label="MAIN_FRAME_REQUEST_STATS_PROCESSED_REDIRECTS"/>
+  <int value="4" label="MAIN_FRAME_REQUEST_STATS_TOTAL_RESPONSES"/>
+  <int value="5" label="MAIN_FRAME_REQUEST_STATS_PROCESSED_RESPONSES"/>
+</enum>
+
+<enum name="ResourcePrefetchPredictorNavigationEvent" type="int">
+  <int value="0" label="NAVIGATION_EVENT_REQUEST_STARTED"/>
+  <int value="1" label="NAVIGATION_EVENT_REQUEST_REDIRECTED"/>
+  <int value="2" label="NAVIGATION_EVENT_REQUEST_REDIRECTED_EMPTY_URL"/>
+  <int value="3" label="NAVIGATION_EVENT_REQUEST_EXPIRED"/>
+  <int value="4" label="NAVIGATION_EVENT_RESPONSE_STARTED"/>
+  <int value="5" label="NAVIGATION_EVENT_ONLOAD"/>
+  <int value="6" label="NAVIGATION_EVENT_ONLOAD_EMPTY_URL"/>
+  <int value="7" label="NAVIGATION_EVENT_ONLOAD_UNTRACKED_URL"/>
+  <int value="8" label="NAVIGATION_EVENT_ONLOAD_TRACKED_URL"/>
+  <int value="9" label="NAVIGATION_EVENT_SHOULD_TRACK_URL"/>
+  <int value="10" label="NAVIGATION_EVENT_SHOULD_NOT_TRACK_URL"/>
+  <int value="11" label="NAVIGATION_EVENT_URL_TABLE_FULL"/>
+  <int value="12" label="NAVIGATION_EVENT_HAVE_PREDICTIONS_FOR_URL"/>
+  <int value="13" label="NAVIGATION_EVENT_NO_PREDICTIONS_FOR_URL"/>
+  <int value="14" label="NAVIGATION_EVENT_MAIN_FRAME_URL_TOO_LONG"/>
+  <int value="15" label="NAVIGATION_EVENT_HOST_TOO_LONG"/>
+</enum>
+
+<enum name="ResourcePrefetchPredictorPageNotPrefetchedNetworkType" type="int">
+  <int value="0" label="CONNECTION_UNKNOWN"/>
+  <int value="1" label="CONNECTION_ETHERNET"/>
+  <int value="2" label="CONNECTION_WIFI"/>
+  <int value="3" label="CONNECTION_2G"/>
+  <int value="4" label="CONNECTION_3G"/>
+  <int value="5" label="CONNECTION_4G"/>
+  <int value="6" label="CONNECTION_NONE"/>
+  <int value="7" label="CONNECTION_BLUETOOTH"/>
+  <int value="8" label="CONNECTION_CELLULAR"/>
+  <int value="9" label="CONNECTION_ALL"/>
+</enum>
+
+<enum name="ResourcePrefetchPredictorPagePrefetchedNetworkType" type="int">
+  <int value="0" label="CONNECTION_UNKNOWN"/>
+  <int value="1" label="CONNECTION_ETHERNET"/>
+  <int value="2" label="CONNECTION_WIFI"/>
+  <int value="3" label="CONNECTION_2G"/>
+  <int value="4" label="CONNECTION_3G"/>
+  <int value="5" label="CONNECTION_4G"/>
+  <int value="6" label="CONNECTION_NONE"/>
+  <int value="7" label="CONNECTION_BLUETOOTH"/>
+  <int value="8" label="CONNECTION_CELLULAR"/>
+  <int value="9" label="CONNECTION_ALL"/>
+</enum>
+
+<enum name="ResourcePrefetchPredictorReportingEvent" type="int">
+  <int value="0" label="REPORTING_EVENT_ALL_HISTORY_CLEARED"/>
+  <int value="1" label="REPORTING_EVENT_PARTIAL_HISTORY_CLEARED"/>
+</enum>
+
+<enum name="ResourcePrefetchPredictorRequestStats" type="int">
+  <int value="0" label="REQUEST_STATS_TOTAL_RESPONSES"/>
+  <int value="1" label="REQUEST_STATS_TOTAL_PROCESSED_RESPONSES"/>
+  <int value="2" label="REQUEST_STATS_NO_RESOURCE_REQUEST_INFO"/>
+  <int value="3" label="REQUEST_STATS_NO_RENDER_VIEW_ID_FROM_REQUEST_INFO"/>
+</enum>
+
+<enum name="ResourcePrefetchPredictorResourceStatus" type="int">
+  <int value="0" label="RESOURCE_STATUS_HANDLED"/>
+  <int value="1" label="RESOURCE_STATUS_NOT_HTTP_PAGE"/>
+  <int value="2" label="RESOURCE_STATUS_NOT_HTTP_RESOURCE"/>
+  <int value="4" label="RESOURCE_STATUS_UNSUPPORTED_MIME_TYPE"/>
+  <int value="8" label="RESOURCE_STATUS_NOT_GET"/>
+  <int value="16" label="RESOURCE_STATUS_URL_TOO_LONG"/>
+  <int value="32" label="RESOURCE_STATUS_NOT_CACHEABLE"/>
+  <int value="64" label="RESOURCE_STATUS_HEADERS_MISSING"/>
+</enum>
+
 <enum name="ResourceType" type="int">
   <int value="0" label="Main resource"/>
   <int value="1" label="Image"/>
@@ -56846,6 +57419,83 @@ To add a new entry, add it with any value and run test to compute valid value.
   <affected-histogram name="Event.Latency.Renderer2"/>
 </histogram_suffixes>
 
+<histogram_suffixes name="ResourcePrefetchPredictorPLTNetworkTypes">
+  <suffix name="2G" label="Page load time in 2G network."/>
+  <suffix name="3G" label="Page load time in 3G network."/>
+  <suffix name="4G" label="Page load time in 4G network."/>
+  <suffix name="Bluetooth" label="Page load time in bluetooth network."/>
+  <suffix name="Cellular" label="Page load time in cellular network."/>
+  <suffix name="Ethernet" label="Page load time in Ethernet."/>
+  <suffix name="None" label="Page load time without network connection."/>
+  <suffix name="Unknown" label="Page load time in unknown type of network."/>
+  <suffix name="WiFi" label="Page load time in WiFi network."/>
+  <affected-histogram name="ResourcePrefetchPredictor.PLT"/>
+  <affected-histogram name="ResourcePrefetchPredictor.PLT.PageNotPrefetched"/>
+  <affected-histogram name="ResourcePrefetchPredictor.PLT.PagePrefetched"/>
+  <affected-histogram name="ResourcePrefetchPredictor.PLT.PagePrefetched.Host"/>
+  <affected-histogram name="ResourcePrefetchPredictor.PLT.PagePrefetched.Url"/>
+</histogram_suffixes>
+
+<histogram_suffixes name="ResourcePrefetchPredictorPredictedStatsTypes">
+  <suffix name="Count" label="Predicted accuracy stats as the raw numbers."/>
+  <suffix name="PercentOfTotalPrefetched"
+      label="Predicted accuracy stats as percent of total resources
+             prefetched."/>
+  <affected-histogram
+      name="ResourcePrefetchPredictor.Host.PredictedPrefetchFromCache"/>
+  <affected-histogram
+      name="ResourcePrefetchPredictor.Host.PredictedPrefetchFromNetwork"/>
+  <affected-histogram
+      name="ResourcePrefetchPredictor.Host.PredictedPrefetchMisses"/>
+  <affected-histogram
+      name="ResourcePrefetchPredictor.Url.PredictedPrefetchFromCache"/>
+  <affected-histogram
+      name="ResourcePrefetchPredictor.Url.PredictedPrefetchFromNetwork"/>
+  <affected-histogram
+      name="ResourcePrefetchPredictor.Url.PredictedPrefetchMisses"/>
+</histogram_suffixes>
+
+<histogram_suffixes name="ResourcePrefetchPredictorPredictedStatsVariedMax">
+  <suffix name="25"
+      label="Covers statistics when the maximum subresources that can be
+             prefetched is set to 25."/>
+  <suffix name="50"
+      label="Covers statistics when the maximum subresources that can be
+             prefetched is set to 50."/>
+  <affected-histogram
+      name="ResourcePrefetchPredictor.Host.PredictedPrefetchCount"/>
+  <affected-histogram
+      name="ResourcePrefetchPredictor.Host.PredictedPrefetchFromCache_Count"/>
+  <affected-histogram
+      name="ResourcePrefetchPredictor.Host.PredictedPrefetchFromCache_PercentOfTotalPrefetched"/>
+  <affected-histogram
+      name="ResourcePrefetchPredictor.Host.PredictedPrefetchFromNetwork_Count"/>
+  <affected-histogram
+      name="ResourcePrefetchPredictor.Host.PredictedPrefetchFromNetwork_PercentOfTotalPrefetched"/>
+  <affected-histogram
+      name="ResourcePrefetchPredictor.Host.PredictedPrefetchFromNetworkPercentOfTotalFromNetwork"/>
+  <affected-histogram
+      name="ResourcePrefetchPredictor.Host.PredictedPrefetchMisses_Count"/>
+  <affected-histogram
+      name="ResourcePrefetchPredictor.Host.PredictedPrefetchMisses_PercentOfTotalPrefetched"/>
+  <affected-histogram
+      name="ResourcePrefetchPredictor.Url.PredictedPrefetchCount"/>
+  <affected-histogram
+      name="ResourcePrefetchPredictor.Url.PredictedPrefetchFromCache_Count"/>
+  <affected-histogram
+      name="ResourcePrefetchPredictor.Url.PredictedPrefetchFromCache_PercentOfTotalPrefetched"/>
+  <affected-histogram
+      name="ResourcePrefetchPredictor.Url.PredictedPrefetchFromNetwork_Count"/>
+  <affected-histogram
+      name="ResourcePrefetchPredictor.Url.PredictedPrefetchFromNetwork_PercentOfTotalPrefetched"/>
+  <affected-histogram
+      name="ResourcePrefetchPredictor.Url.PredictedPrefetchFromNetworkPercentOfTotalFromNetwork"/>
+  <affected-histogram
+      name="ResourcePrefetchPredictor.Url.PredictedPrefetchMisses_Count"/>
+  <affected-histogram
+      name="ResourcePrefetchPredictor.Url.PredictedPrefetchMisses_PercentOfTotalPrefetched"/>
+</histogram_suffixes>
+
 <histogram_suffixes name="SBInterstitial">
   <obsolete>
     deprecated November 10 2012 crrev.com/167056