Add TimeToScrollUpdateSwapBegin2 in RAPPOR

tools/metrics/rappor/rappor.xml

Index: tools/metrics/rappor/rappor.xml
diff --git a/tools/metrics/rappor/rappor.xml b/tools/metrics/rappor/rappor.xml
index c3e088e3fcd1a54539c7350d4ab8f50474eba482..e03bfcad9852ab1db0dc8f445413fea844ead2d8 100644
--- a/tools/metrics/rappor/rappor.xml
+++ b/tools/metrics/rappor/rappor.xml
@@ -909,6 +909,35 @@ components/rappor/rappor_parameters.h.
   </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>