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

content/renderer/input/input_event_filter.h

 // Copyright 2013 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.
 
 #ifndef CONTENT_RENDERER_INPUT_INPUT_EVENT_FILTER_H_
 #define CONTENT_RENDERER_INPUT_INPUT_EVENT_FILTER_H_
 
 #include <queue>
 #include <set>
 #include <unordered_map>
@@ skipping 63 matching lines @@
   void OnFilterRemoved() override;
   void OnChannelClosing() override;
   bool OnMessageReceived(const IPC::Message& message) override;
 
   // MainThreadEventQueueClient methods:
   void SendEventToMainThread(int routing_id,
                              const blink::WebInputEvent* event,
                              const ui::LatencyInfo& latency,
                              InputEventDispatchType dispatch_type) override;
 
+  // Whether the fling animation is happening right now.
+  void SetIsFlinging(bool is_flinging) override;
+
  private:
   ~InputEventFilter() override;
 
   void ForwardToHandler(const IPC::Message& message);
   void SendMessage(std::unique_ptr<IPC::Message> message);
   void SendMessageOnIOThread(std::unique_ptr<IPC::Message> message);
 
   scoped_refptr<base::SingleThreadTaskRunner> main_task_runner_;
   base::Callback<void(const IPC::Message&)> main_listener_;
 
@@ skipping 13 matching lines @@
 
   using RouteQueueMap =
       std::unordered_map<int, std::unique_ptr<MainThreadEventQueue>>;
   RouteQueueMap route_queues_;
 
   // Used to intercept overscroll notifications while an event is being
   // dispatched.  If the event causes overscroll, the overscroll metadata can be
   // bundled in the event ack, saving an IPC.  Note that we must continue
   // supporting overscroll IPC notifications due to fling animation updates.
   std::unique_ptr<DidOverscrollParams>* current_overscroll_params_;
+
+  bool is_flinging_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_INPUT_INPUT_EVENT_FILTER_H_