Signal input flush when all flings have terminated

content/browser/renderer_host/input/gesture_event_queue.h

Index: content/browser/renderer_host/input/gesture_event_queue.h
diff --git a/content/browser/renderer_host/input/gesture_event_queue.h b/content/browser/renderer_host/input/gesture_event_queue.h
index 208b2de457c9c56d3eb8f5cb1453e89a310a5558..693d25d6aa02311d89703ad8fe83acf7efa6f07b 100644
--- a/content/browser/renderer_host/input/gesture_event_queue.h
+++ b/content/browser/renderer_host/input/gesture_event_queue.h
@@ -93,9 +93,8 @@ class CONTENT_EXPORT GestureEventQueue {
                          blink::WebInputEvent::Type type,
                          const ui::LatencyInfo& latency);
 
-  // Sets the state of the |fling_in_progress_| field to indicate that a fling
-  // is definitely not in progress.
-  void FlingHasBeenHalted();
+  // Notify the queue that a gesture fling animation in the renderer has ended.
+  void DidStopFlinging();
 
   // Returns the |TouchpadTapSuppressionController| instance.
   TouchpadTapSuppressionController* GetTouchpadTapSuppressionController();
@@ -107,6 +106,8 @@ class CONTENT_EXPORT GestureEventQueue {
            debouncing_deferral_queue_.empty();
   }
 
+  int active_fling_count() const { return active_fling_count_; }
+
   void set_debounce_interval_time_ms_for_testing(int interval_ms) {
     debounce_interval_ = base::TimeDelta::FromMilliseconds(interval_ms);
   }
@@ -158,9 +159,10 @@ class CONTENT_EXPORT GestureEventQueue {
   // The receiver of all forwarded gesture events.
   GestureEventQueueClient* client_;
 
-  // True if a GestureFlingStart is in progress on the renderer or
-  // queued without a subsequent queued GestureFlingCancel event.
-  bool fling_in_progress_;
+  // Whether there are any active flings in the renderer. As the fling
+  // end notification is asynchronous, we use a count rather than a boolean
+  // to avoid races in bookkeeping when starting a new fling.
+  int active_fling_count_;
 
   // True if a GestureScrollUpdate sequence is in progress.
   bool scrolling_in_progress_;