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

content/renderer/input/main_thread_event_queue.cc

Index: content/renderer/input/main_thread_event_queue.cc
diff --git a/content/renderer/input/main_thread_event_queue.cc b/content/renderer/input/main_thread_event_queue.cc
index 15c83500253cecaca40140ffc35b5668a45f03c1..243bc4fe9508b0386899b6c22929c0e8ebfda206 100644
--- a/content/renderer/input/main_thread_event_queue.cc
+++ b/content/renderer/input/main_thread_event_queue.cc
@@ -8,7 +8,7 @@ namespace content {
 
 MainThreadEventQueue::MainThreadEventQueue(int routing_id,
                                            MainThreadEventQueueClient* client)
-    : routing_id_(routing_id), client_(client) {}
+    : routing_id_(routing_id), client_(client), is_flinging_(false) {}
 
 MainThreadEventQueue::~MainThreadEventQueue() {}
 
@@ -63,6 +63,7 @@ bool MainThreadEventQueue::HandleEvent(
     PendingTouchEvent modified_dispatch_type_event =
         PendingTouchEvent(*static_cast<const blink::WebTouchEvent*>(event),
                           latency, dispatch_type);
+    modified_dispatch_type_event.event.dispatchedDuringFling = is_flinging_;
 
     // Adjust the |dispatchType| on the event since the compositor
     // determined all event listeners are passive.