Measure queueing and blocking time for touchstart/touchend.

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 7a68be2e2bcc8f2cdf5caf63f663a693cd7714f1..9e48bc9313946733b3cf40561e3cc7e457939bb4 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -12100,8 +12100,24 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
-<histogram name="Event.Latency.BlockingTime.TouchMoveDefaultAllowed"
-    units="microseconds">

[Ilya Sherman, 2016/06/10 23:22:37]

Just to confirm, the units previously listed were inaccurate, and there's
otherwise no change to the pre-existing histogram?  If so, LGTM.  If not, then
let's discuss further.

+<histogram name="Event.Latency.BlockingTime.TouchEndDefaultAllowed" units="ms">
+  <owner>tdresser@chromium.org</owner>
+  <summary>
+    Time between the renderer main thread receiving a touchend event and acking
+    it, for events which were not preventDefaulted.
+  </summary>
+</histogram>
+
+<histogram name="Event.Latency.BlockingTime.TouchEndDefaultPrevented"
+    units="ms">
+  <owner>tdresser@chromium.org</owner>
+  <summary>
+    Time between the renderer main thread receiving a touchend event and acking
+    it, for events which were preventDefaulted.
+  </summary>
+</histogram>
+
+<histogram name="Event.Latency.BlockingTime.TouchMoveDefaultAllowed" units="ms">
   <owner>tdresser@chromium.org</owner>
   <summary>
     Time between the renderer main thread receiving a touchmove event and acking
@@ -12110,7 +12126,7 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 </histogram>
 
 <histogram name="Event.Latency.BlockingTime.TouchMoveDefaultPrevented"
-    units="microseconds">
+    units="ms">
   <owner>tdresser@chromium.org</owner>
   <summary>
     Time between the renderer main thread receiving a touchmove event and acking
@@ -12118,6 +12134,24 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Event.Latency.BlockingTime.TouchStartDefaultAllowed"
+    units="ms">
+  <owner>tdresser@chromium.org</owner>
+  <summary>
+    Time between the renderer main thread receiving a touchstart event and
+    acking it, for events which were not preventDefaulted.
+  </summary>
+</histogram>
+
+<histogram name="Event.Latency.BlockingTime.TouchStartDefaultPrevented"
+    units="ms">
+  <owner>tdresser@chromium.org</owner>
+  <summary>
+    Time between the renderer main thread receiving a touchstart event and
+    acking it, for events which were preventDefaulted.
+  </summary>
+</histogram>
+
 <histogram name="Event.Latency.Browser" units="microseconds">
   <owner>rbyers@chromium.org</owner>
   <summary>
@@ -12454,8 +12488,26 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>Time between input event received by OS and sent to Chrome.</summary>
 </histogram>
 
-<histogram name="Event.Latency.QueueingTime.TouchMoveDefaultAllowed"
-    units="microseconds">
+<histogram name="Event.Latency.QueueingTime.TouchEndDefaultAllowed" units="ms">
+  <owner>tdresser@chromium.org</owner>
+  <summary>
+    Time between sending a touchend event to the renderer main thread and when
+    the renderer begins to process that event, for events which were not
+    preventDefaulted.
+  </summary>
+</histogram>
+
+<histogram name="Event.Latency.QueueingTime.TouchEndDefaultPrevented"
+    units="ms">
+  <owner>tdresser@chromium.org</owner>
+  <summary>
+    Time between sending a touchend event to the renderer main thread and when
+    the renderer begins to process that event, for events which were
+    preventDefaulted.
+  </summary>
+</histogram>
+
+<histogram name="Event.Latency.QueueingTime.TouchMoveDefaultAllowed" units="ms">
   <owner>tdresser@chromium.org</owner>
   <summary>
     Time between sending a touchmove event to the renderer main thread and when
@@ -12465,7 +12517,7 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 </histogram>
 
 <histogram name="Event.Latency.QueueingTime.TouchMoveDefaultPrevented"
-    units="microseconds">
+    units="ms">
   <owner>tdresser@chromium.org</owner>
   <summary>
     Time between sending a touchmove event to the renderer main thread and when
@@ -12474,6 +12526,26 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Event.Latency.QueueingTime.TouchStartDefaultAllowed"
+    units="ms">
+  <owner>tdresser@chromium.org</owner>
+  <summary>
+    Time between sending a touchstart event to the renderer main thread and when
+    the renderer begins to process that event, for events which were not
+    preventDefaulted.
+  </summary>
+</histogram>
+
+<histogram name="Event.Latency.QueueingTime.TouchStartDefaultPrevented"
+    units="ms">
+  <owner>tdresser@chromium.org</owner>
+  <summary>
+    Time between sending a touchstart event to the renderer main thread and when
+    the renderer begins to process that event, for events which were
+    preventDefaulted.
+  </summary>
+</histogram>
+
 <histogram name="Event.Latency.Renderer" units="microseconds">
   <owner>rbyers@chromium.org</owner>
   <summary>