Support Coalesced Touch in ppapi

third_party/WebKit/Source/core/input/PointerEventManager.cpp

 // 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 "core/input/PointerEventManager.h"
 
 #include "core/dom/DocumentUserGestureToken.h"
 #include "core/dom/ElementTraversal.h"
 #include "core/dom/shadow/FlatTreeTraversal.h"
 #include "core/events/MouseEvent.h"
@@ skipping 300 matching lines @@
   if (event.GetType() == WebInputEvent::kTouchEnd &&
       !in_canceled_state_for_pointer_type_touch_ && !touch_infos.IsEmpty() &&
       touch_infos[0].target_frame) {
     possible_gesture_token = DocumentUserGestureToken::Create(
         touch_infos[0].target_frame->GetDocument());
   }
   UserGestureIndicator holder(possible_gesture_token);
 
   DispatchTouchPointerEvents(event, coalesced_events, touch_infos);
 
-  return touch_event_manager_->HandleTouchEvent(event, touch_infos);
+  return touch_event_manager_->HandleTouchEvent(event, coalesced_events,

[Navid Zolghadr, 2017/05/01 15:53:33]

This is unlikely that we keep this coalesced_events variable here as we are in
the process of removing the coalesced touch events altogether and just keep the
coalesced pointer events. In that case we will not have the grouping for the
coalesced touch events anymore.

[jkwang, 2017/05/02 18:59:15]

Is there a time line of removing coalesced touch events?
If coalesced touch event is not available any more. We can build the touch
events from coalesced pointer events. The goal is to report the trace of all
touch points, so we can see touch event as a snapshot of "multiple pointer event
streams". 
I am not sure what I can do now to make things easier(and correct). But if we
can make the change when we remove the coalesced touch events, I think it's OK
to leave it like this. 

+                                                touch_infos);
 }
 
 void PointerEventManager::ComputeTouchTargets(
     const WebTouchEvent& event,
     HeapVector<TouchEventManager::TouchInfo>& touch_infos) {
   for (unsigned touch_point = 0; touch_point < event.touches_length;
        ++touch_point) {
     TouchEventManager::TouchInfo touch_info;
     touch_info.point = event.TouchPointInRootFrame(touch_point);
 
@@ skipping 379 matching lines @@
     if (first_id > unique_touch_event_id)
       return false;
     touch_ids_for_canceled_pointerdowns_.TakeFirst();
     if (first_id == unique_touch_event_id)
       return true;
   }
   return false;
 }
 
 }  // namespace blink