NQE: Add accuracy histogram for external estimate provider

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 d9ccb7ac4b17da347a488e03a2ff8d66a105ce88..85f906afde065e0f446b5153a9ca82255b2b9fcf 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -35572,6 +35572,20 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram
+    name="NQE.ExternalEstimateProvider.RTT.Accuracy.EstimatedObservedDiff"
+    units="ms">
+  <owner>tbansal@chromium.org</owner>
+  <owner>bengr@chromium.org</owner>
+  <summary>
+    Records the difference between the HTTP RTT estimated by external estimate

[bengr, 2016/07/20 23:51:28]

by -> by the

[tbansal1, 2016/07/21 22:00:50]

Done.

+    provider and the observed HTTP RTT. HTTP RTT estimated by the external

[bengr, 2016/07/20 23:51:28]

HTTP RTT -> The HTTP RTT

[tbansal1, 2016/07/21 22:00:51]

Done.

+    estimate provider at the time of navigation start is compared with the HTTP
+    RTT observed during the specified time interval following the start of the
+    navigation.
+  </summary>
+</histogram>
+
 <histogram name="NQE.ExternalEstimateProviderStatus"
     enum="NQEExternalEstimateProviderStatus">
   <owner>bengr@chromium.org</owner>
@@ -97982,6 +97996,8 @@ To add a new entry, add it with any value and run test to compute valid value.
       name="NQE.Accuracy.EffectiveConnectionType.EstimatedObservedDiff"/>
   <affected-histogram name="NQE.Accuracy.HttpRTT.EstimatedObservedDiff"/>
   <affected-histogram name="NQE.Accuracy.TransportRTT.EstimatedObservedDiff"/>
+  <affected-histogram
+      name="NQE.ExternalEstimateProvider.RTT.Accuracy.EstimatedObservedDiff"/>
 </histogram_suffixes>
 
 <histogram_suffixes name="NQE.Accuracy.Metric.AccuracyRecordingIntervals"
@@ -98008,6 +98024,10 @@ To add a new entry, add it with any value and run test to compute valid value.
       name="NQE.Accuracy.TransportRTT.EstimatedObservedDiff.Negative"/>
   <affected-histogram
       name="NQE.Accuracy.TransportRTT.EstimatedObservedDiff.Positive"/>
+  <affected-histogram
+      name="NQE.ExternalEstimateProvider.RTT.Accuracy.EstimatedObservedDiff.Negative"/>
+  <affected-histogram
+      name="NQE.ExternalEstimateProvider.RTT.Accuracy.EstimatedObservedDiff.Positive"/>
 </histogram_suffixes>
 
 <histogram_suffixes
@@ -98092,6 +98112,18 @@ To add a new entry, add it with any value and run test to compute valid value.
       name="NQE.Accuracy.TransportRTT.EstimatedObservedDiff.Positive.30"/>
   <affected-histogram
       name="NQE.Accuracy.TransportRTT.EstimatedObservedDiff.Positive.60"/>
+  <affected-histogram
+      name="NQE.ExternalEstimateProvider.RTT.Accuracy.EstimatedObservedDiff.Negative.15"/>
+  <affected-histogram
+      name="NQE.ExternalEstimateProvider.RTT.Accuracy.EstimatedObservedDiff.Negative.30"/>
+  <affected-histogram
+      name="NQE.ExternalEstimateProvider.RTT.Accuracy.EstimatedObservedDiff.Negative.60"/>
+  <affected-histogram
+      name="NQE.ExternalEstimateProvider.RTT.Accuracy.EstimatedObservedDiff.Positive.15"/>
+  <affected-histogram
+      name="NQE.ExternalEstimateProvider.RTT.Accuracy.EstimatedObservedDiff.Positive.30"/>
+  <affected-histogram
+      name="NQE.ExternalEstimateProvider.RTT.Accuracy.EstimatedObservedDiff.Positive.60"/>
 </histogram_suffixes>
 
 <histogram_suffixes name="NQE.DifferentPercentiles" separator=".">