Cleanup expired histogram: Event.FrameEventRouting.TouchEventAckQueueSize.

Bug: 1092510
Change-Id: I0b7d7c4ea94f91767fd2a4e6c7c807bfc73a8fda
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2490226Reviewed-by: Alex Moshchuk <alexmos@chromium.org>
Reviewed-by: Jesse Doherty <jwd@chromium.org>
Commit-Queue: James MacLean <wjmaclean@chromium.org>
Cr-Commit-Position: refs/heads/master@{#819828}

content/browser/renderer_host/render_widget_host_input_event_router.cc

@@ -123,7 +123,6 @@ class TouchEventAckQueue {
 
  private:
   void ProcessAckedTouchEvents();
-  void ReportTouchEventAckQueueUmaStats();
 
   std::deque<AckData> ack_queue_;
   RenderWidgetHostInputEventRouter* client_;
@@ -144,7 +143,6 @@ void TouchEventAckQueue::Add(const TouchEventWithLatencyInfo& touch_event,
   ack_queue_.push_back(data);
   if (touch_event_ack_status == TouchEventAckStatus::TouchEventAcked)
     ProcessAckedTouchEvents();
-  ReportTouchEventAckQueueUmaStats();
 }
 
 void TouchEventAckQueue::Add(const TouchEventWithLatencyInfo& touch_event,
@@ -206,14 +204,6 @@ void TouchEventAckQueue::ProcessAckedTouchEvents() {
   }
 }
 
-void TouchEventAckQueue::ReportTouchEventAckQueueUmaStats() {
-  size_t count = ack_queue_.size();
-  UMA_HISTOGRAM_COUNTS_10000("Event.FrameEventRouting.TouchEventAckQueueSize",
-                             count);
-  // TODO(wjmaclean): is it worth also recording how many different renderers
-  // are waiting on touch event acks at the time of reporting?
-}
-
 void TouchEventAckQueue::UpdateQueueAfterTargetDestroyed(
     RenderWidgetHostViewBase* target_view) {
   // If a queue entry's root view is being destroyed, just delete it.

tools/metrics/histograms/histograms_xml/event/histograms.xml

@@ -148,6 +148,9 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 
 <histogram name="Event.FrameEventRouting.TouchEventAckQueueSize" units="units"
     expires_after="2020-07-19">
+  <obsolete>
+    2020.10.21 - Removed.
+  </obsolete>
   <owner>wjmaclean@chromium.org</owner>
   <owner>kenrb@chromium.org</owner>
   <summary>