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

content/renderer/input/main_thread_event_queue.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/input/main_thread_event_queue.h"
 
 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() {}
 
 bool MainThreadEventQueue::HandleEvent(
     const blink::WebInputEvent* event,
     const ui::LatencyInfo& latency,
     InputEventDispatchType original_dispatch_type,
     InputEventAckState ack_result) {
   DCHECK(original_dispatch_type == DISPATCH_TYPE_BLOCKING ||
          original_dispatch_type == DISPATCH_TYPE_NON_BLOCKING);
@@ skipping 34 matching lines @@
         // having the main thread call us back as an optimization.
         client_->SendEventToMainThread(routing_id_,
                                        &modified_dispatch_type_event.event,
                                        latency, original_dispatch_type);
       }
     }
   } else if (blink::WebInputEvent::isTouchEventType(event->type)) {
     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.
     if (non_blocking) {
       modified_dispatch_type_event.event.dispatchType =
           blink::WebInputEvent::ListenersNonBlockingPassive;
     }
 
     if (touch_events_.state() == WebInputEventQueueState::ITEM_PENDING) {
       touch_events_.Queue(modified_dispatch_type_event);
@@ skipping 37 matching lines @@
                                      event->type);
     } else {
       touch_events_.set_state(WebInputEventQueueState::ITEM_NOT_PENDING);
     }
   } else {
     NOTREACHED() << "Invalid passive event type";
   }
 }
 
 }  // namespace content