Record NQE accuracy at main frame requests

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 e27be831c1d97deee5003d779751ae1067c2dc53..fe32b6c07a90a6af4c9a9254cd3d8a4ee446143c 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -34484,6 +34484,56 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="NQE.Accuracy.HttpRTT.ActualEstimatedDiff" units="ms">
+  <owner>tbansal@chromium.org</owner>
+  <owner>bengr@chromium.org</owner>
+  <summary>
+    Records the difference between the observed HTTP RTT and the actual HTTP

[Alexei Svitkine (slow), 2016/06/03 20:01:07]

I find these histogram names super confusing - and the descriptions also confuse
me. :\

In the names, you have the terms "estimated" and "actual". But in the
descriptions you have "observed", "actual", "estimated".

Can we avoid these inconsistencies? i.e. have the names correspond more closely
to the descriptions? The description also use the word "predicted" - is this
different as well from estimated, or are some of these synonyms? What's the
difference between observed and actual?

For example, if a histogram is measuring the difference between two things,
maybe that's how it should be called? e.g. DiffActualVsEstimate?

Looking at your code, maybe you're just using the two names because histograms
don't support logging negatives. If so, maybe it would be clearer to just have
suffixes for the same histogram name? e.g. .Positive vs. .Negative?

[tbansal1, 2016/06/03 20:57:20]

Fixed it to use "estimated" and "observed" every where. There is one function
(not touched by this CL) that uses "actual" but that function and the
corresponding histograms will go away in the next CL.
observed = actual
estimated = predicted
But, now it should all be "estimated" and "observed".
Using the suffix now.

+    RTT. HTTP RTT predicted by the network quality estimator at the time of
+    navigation start is compared with the HTTP RTT observed during the specified
+    time interval following the start of the navigation. This metric is recorded
+    only when the estimated RTT is lower than the observed RTT.
+  </summary>
+</histogram>
+
+<histogram name="NQE.Accuracy.HttpRTT.EstimatedActualDiff" units="ms">
+  <owner>tbansal@chromium.org</owner>
+  <owner>bengr@chromium.org</owner>
+  <summary>
+    Records the difference between the estimated HTTP RTT and the observed HTTP
+    RTT. HTTP RTT predicted by the network quality estimator at the time of
+    navigation start is compared with the HTTP RTT observed during the specified
+    time interval following the start of the navigation. This metric is recorded
+    only when the estimated RTT is at least as high as observed RTT.
+  </summary>
+</histogram>
+
+<histogram name="NQE.Accuracy.TransportRTT.ActualEstimatedDiff" units="ms">
+  <owner>tbansal@chromium.org</owner>
+  <owner>bengr@chromium.org</owner>
+  <summary>
+    Records the difference between the observed transport RTT and the actual
+    transport RTT. Transport RTT predicted by the network quality estimator at
+    the time of navigation start is compared with the transport RTT observed
+    during the specified time interval following the start of the navigation.
+    This metric is recorded only when the estimated RTT is lower than the
+    observed RTT.
+  </summary>
+</histogram>
+
+<histogram name="NQE.Accuracy.TransportRTT.EstimatedActualDiff" units="ms">
+  <owner>tbansal@chromium.org</owner>
+  <owner>bengr@chromium.org</owner>
+  <summary>
+    Records the difference between the estimated transport RTT and the observed
+    transport RTT. Transport RTT predicted by the network quality estimator at
+    the time of navigation start is compared with the transport RTT observed
+    during the specified time interval following the start of the navigation.
+    This metric is recorded only when the estimated RTT is at least as high as
+    observed RTT.
+  </summary>
+</histogram>
+
 <histogram name="NQE.DifferenceRTTActualAndEstimated" units="ms">
   <owner>bengr@chromium.org</owner>
   <owner>tbansal@chromium.org</owner>
@@ -95057,6 +95107,53 @@ To add a new entry, add it with any value and run test to compute valid value.
   <affected-histogram name="Tabs.StateTransfer.Time_Inactive"/>
 </histogram_suffixes>
 
+<histogram_suffixes name="NQE.Accuracy.RTT.AccuracyRecordingIntervals"
+    separator=".">
+  <suffix name="15"
+      label="Recorded approximately 15 seconds after navigation start"/>
+  <suffix name="30"
+      label="Recorded approximately 30 seconds after navigation start"/>
+  <suffix name="60"
+      label="Recorded approximately 60 seconds after navigation start"/>
+  <affected-histogram name="NQE.Accuracy.HttpRTT.ActualEstimatedDiff"/>
+  <affected-histogram name="NQE.Accuracy.HttpRTT.EstimatedActualDiff"/>
+  <affected-histogram name="NQE.Accuracy.TransportRTT.ActualEstimatedDiff"/>
+  <affected-histogram name="NQE.Accuracy.TransportRTT.EstimatedActualDiff"/>
+</histogram_suffixes>
+
+<histogram_suffixes name="NQE.Accuracy.RTT.ObservedRTTIntervals" separator=".">
+  <suffix name="0_20"
+      label="Observed RTT was between 0 and 20 (inclusive) msec"/>
+  <suffix name="20_60"
+      label="Observed RTT was between 20 and 60 (inclusive) msec"/>
+  <suffix name="60_140"
+      label="Observed RTT was between 60 and 140 (inclusive) msec"/>
+  <suffix name="140_300"
+      label="Observed RTT was between 140 and 300 (inclusive) msec"/>
+  <suffix name="300_620"
+      label="Observed RTT was between 300 and 620 (inclusive) msec"/>
+  <suffix name="620_1260"
+      label="Observed RTT was between 620 and 1260 (inclusive) msec"/>
+  <suffix name="1260_2540"
+      label="Observed RTT was between 1260 and 2540 (inclusive) msec"/>
+  <suffix name="2540_5100"
+      label="Observed RTT was between 2540 and 51000 (inclusive) msec"/>
+  <suffix name="5100_Infinity"
+      label="Observed RTT was greater than 5100 (inclusive) msec"/>
+  <affected-histogram name="NQE.Accuracy.HttpRTT.ActualEstimatedDiff.15"/>
+  <affected-histogram name="NQE.Accuracy.HttpRTT.ActualEstimatedDiff.30"/>
+  <affected-histogram name="NQE.Accuracy.HttpRTT.ActualEstimatedDiff.60"/>
+  <affected-histogram name="NQE.Accuracy.HttpRTT.EstimatedActualDiff.15"/>
+  <affected-histogram name="NQE.Accuracy.HttpRTT.EstimatedActualDiff.30"/>
+  <affected-histogram name="NQE.Accuracy.HttpRTT.EstimatedActualDiff.60"/>
+  <affected-histogram name="NQE.Accuracy.TransportRTT.ActualEstimatedDiff.15"/>
+  <affected-histogram name="NQE.Accuracy.TransportRTT.ActualEstimatedDiff.30"/>
+  <affected-histogram name="NQE.Accuracy.TransportRTT.ActualEstimatedDiff.60"/>
+  <affected-histogram name="NQE.Accuracy.TransportRTT.EstimatedActualDiff.15"/>
+  <affected-histogram name="NQE.Accuracy.TransportRTT.EstimatedActualDiff.30"/>
+  <affected-histogram name="NQE.Accuracy.TransportRTT.EstimatedActualDiff.60"/>
+</histogram_suffixes>
+
 <histogram_suffixes name="NQE.DifferentPercentiles" separator=".">
   <suffix name="Percentile0" label="0th percentile"/>
   <suffix name="Percentile10" label="10th percentile"/>