Add TimeToScrollUpdateSwapBegin2 in RAPPOR

tools/metrics/rappor/rappor.xml

 <!--
 Copyright 2015 The Chromium Authors. All rights reserved.
 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 Chrome rappor metrics
 along with a detailed description for each histogram. See the design doc at
 http://www.chromium.org/developers/design-documents/rappor
@@ skipping 891 matching lines @@
   </summary>
 </rappor-metric>
 
 <rappor-metric name="DomDistiller.PromptPanel" type="UMA_RAPPOR_TYPE">
   <owner>wychen@chromium.org</owner>
   <summary>
     The eTLD+1 of the frame URL where Reader Mode is prompted.
   </summary>
 </rappor-metric>
 
+<rappor-metric
+    name="Event.Latency.ScrollUpdate.Touch.TimeToScrollUpdateSwapBegin2.Rappor"

[Navid Zolghadr, 2016/11/10 21:49:19]

Steven, can these name be the same as the ones we use for UMA assuming they are
being reported differently and different paths? Can I just remove the ".rappor"
at the end then?

[Steven Holte, 2016/11/10 22:49:45]

There shouldn't be any issues with using the same name as a histogram.

+    type="UMA_RAPPOR_TYPE">
+  <owner>nzolghadr@chromium.org</owner>
+  <owner>tdresser@chromium.org</owner>
+  <summary>
+    The eTLD+1 of the website visited, along with a bitfield representing bucket
+    membership in a coarse histogram of Touch.TimeToScrollUpdateSwapBegin2.

[Navid Zolghadr, 2016/11/10 21:49:19]

Tim, can you suggest something for the description of the metric? I couldn't
find any existing description for the UMA version.

[tdresser, 2016/11/12 19:23:30]

From histograms.xml.
    Time between initial creation of a touch event and the start of the frame
    swap on the GPU service caused by the generated ScrollUpdate gesture event
    if that ScrollUpdate is the first such event in a given scroll gesture event
    sequence. If no swap was induced by the event, no recording is made.

+  </summary>
+  <string-field name="Domain">
+    <summary>
+      The domain+registry of the URL.
+    </summary>
+  </string-field>
+  <flags-field name="Bucket">
+    <flag bit="0" label="0_10_MILISECONDS"/>
+    <flag bit="1" label="10_20_MILISECONDS"/>
+    <flag bit="2" label="20_30_MILISECONDS"/>
+    <flag bit="3" label="30_40_MILISECONDS"/>
+    <flag bit="4" label="40_50_MILISECONDS"/>
+    <flag bit="5" label="50_60_MILISECONDS"/>
+    <flag bit="6" label="60_70_MILISECONDS"/>
+    <flag bit="7" label="70_INF_SECONDS"/>
+    <summary>
+      Bitfield representing the bucket for Touch.TimeToScrollUpdateSwapBegin.
+    </summary>
+  </flags-field>
+</rappor-metric>
+
 <rappor-metric name="Extensions.AffectedByIsolateExtensions"
     type="UMA_RAPPOR_TYPE">
   <owner>nick@chromium.org</owner>
   <summary>
     The ID of an extension which will trigger out-of-process iframes under
     --isolate-extensions. This metric is logged even if --isolate-extensions is
     disabled. Includes framing in both directions: non-extension documents that
     contain chrome-extension:// iframes, or vice versa. Hosted apps are not
     considered extensions for the purposes of this metric.
   </summary>
@@ skipping 1213 matching lines @@
     <flag bit="1" label="IS_REPEAT_VISIT"/>
     <summary>
       Bitfield of the state from an SSL warning interstitial.
     </summary>
   </flags-field>
 </rappor-metric>
 
 </rappor-metrics>
 
 </rappor-configuration>