Adjust cancelabilty of touchmoves that are queued when scroll start occurs

content/renderer/input/main_thread_event_queue_task.h

Index: content/renderer/input/main_thread_event_queue_task.h
diff --git a/content/renderer/input/main_thread_event_queue_task.h b/content/renderer/input/main_thread_event_queue_task.h
index 64fc0ade70d212d9b9fd714f76c97a431d6252af..9d1c04538eb467fcfdfc5e1f98f6e986f285fad6 100644
--- a/content/renderer/input/main_thread_event_queue_task.h
+++ b/content/renderer/input/main_thread_event_queue_task.h
@@ -21,17 +21,18 @@ class MainThreadEventQueueTask {
  public:
   virtual ~MainThreadEventQueueTask() {}
 
-  enum class CoalesceResult {
-    Coalesced,
-    CannotCoalesce,
-    // Keep iterating on the queue looking for a matching event with the
-    // same modality.
-    KeepSearching,
+  enum class FilterResult {
+    PreventQueuingEvent,
+    StopIterating,
+    KeepIterating,
   };
 
-  virtual CoalesceResult CoalesceWith(const MainThreadEventQueueTask&) = 0;
+  // Filter a new event that is about to be queued. Acceptable actions
+  // are to prevent queuing the event, stop iterating or keep iterating.

[tdresser, 2017/03/31 20:50:20]

Add more detail around what it means to keep iterating. How is this intended to
be used?

[dtapuska, 2017/03/31 21:06:10]

Done.

+  virtual FilterResult FilterNewEvent(const MainThreadEventQueueTask&) = 0;
   virtual bool IsWebInputEvent() const = 0;
   virtual void Dispatch(int routing_id, MainThreadEventQueueClient*) = 0;
+
   virtual void EventHandled(
       int routing_id,
       blink::scheduler::RendererScheduler* renderer_scheduler,