Add UMA metric for tracking listeners for blocking touch while fling is happening

content/browser/renderer_host/input/touch_event_queue.cc

Index: content/browser/renderer_host/input/touch_event_queue.cc
diff --git a/content/browser/renderer_host/input/touch_event_queue.cc b/content/browser/renderer_host/input/touch_event_queue.cc
index 7fb04c5d5986087819c4c205e8a1c764bec6077d..47b7d55f81d7d6f4e98334f16366e7a83e6de100 100644
--- a/content/browser/renderer_host/input/touch_event_queue.cc
+++ b/content/browser/renderer_host/input/touch_event_queue.cc
@@ -346,11 +346,17 @@ class TouchEventQueue::TouchMoveSlopSuppressor {
 class CoalescedWebTouchEvent {
  public:
   CoalescedWebTouchEvent(const TouchEventWithLatencyInfo& event,
-                         bool suppress_client_ack)
+                         bool suppress_client_ack,
+                         bool fling_in_progress)
       : coalesced_event_(event), suppress_client_ack_(suppress_client_ack) {
     TRACE_EVENT_ASYNC_BEGIN0("input", "TouchEventQueue::QueueEvent", this);
+    coalesced_event_.event.isFlingInProgress = fling_in_progress;
   }
 
+  CoalescedWebTouchEvent(const TouchEventWithLatencyInfo& event,
+                         bool suppress_client_ack)
+      : CoalescedWebTouchEvent(event, suppress_client_ack, false) {}
+
   ~CoalescedWebTouchEvent() {
     TRACE_EVENT_ASYNC_END0("input", "TouchEventQueue::QueueEvent", this);
   }
@@ -440,7 +446,8 @@ TouchEventQueue::TouchEventQueue(TouchEventQueueClient* client,
       drop_remaining_touches_in_sequence_(false),
       touchmove_slop_suppressor_(new TouchMoveSlopSuppressor),
       send_touch_events_async_(false),
-      last_sent_touch_timestamp_sec_(0) {
+      last_sent_touch_timestamp_sec_(0),
+      fling_in_progress_(false) {
   DCHECK(client);
   if (config.touch_ack_timeout_supported) {
     timeout_handler_.reset(
@@ -475,7 +482,8 @@ void TouchEventQueue::QueueEvent(const TouchEventWithLatencyInfo& event) {
 
     // There is no touch event in the queue. Forward it to the renderer
     // immediately.
-    touch_queue_.push_back(new CoalescedWebTouchEvent(event, false));
+    touch_queue_.push_back(
+        new CoalescedWebTouchEvent(event, false, fling_in_progress_));
     ForwardNextEventToRenderer();
     return;
   }
@@ -487,7 +495,8 @@ void TouchEventQueue::QueueEvent(const TouchEventWithLatencyInfo& event) {
     if (last_event->CoalesceEventIfPossible(event))
       return;
   }
-  touch_queue_.push_back(new CoalescedWebTouchEvent(event, false));
+  touch_queue_.push_back(
+      new CoalescedWebTouchEvent(event, false, fling_in_progress_));
 }
 
 void TouchEventQueue::PrependTouchScrollNotification() {
@@ -666,6 +675,11 @@ void TouchEventQueue::FlushPendingAsyncTouchmove() {
 
 void TouchEventQueue::OnGestureScrollEvent(
     const GestureEventWithLatencyInfo& gesture_event) {
+  if (gesture_event.event.type == WebInputEvent::GestureFlingStart)
+    fling_in_progress_ = true;
+  else if (gesture_event.event.type == WebInputEvent::GestureFlingCancel)
+    fling_in_progress_ = false;
+
   if (gesture_event.event.type == blink::WebInputEvent::GestureScrollBegin) {
     if (has_handler_for_current_sequence_ &&
         !drop_remaining_touches_in_sequence_) {