Remove WebTouchEvent from TouchEventManager APIs

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

Index: third_party/WebKit/Source/core/input/TouchEventManager.cpp
diff --git a/third_party/WebKit/Source/core/input/TouchEventManager.cpp b/third_party/WebKit/Source/core/input/TouchEventManager.cpp
index 6f6476f60c4d100c5cb68e7b6be1f0963f8a3882..b46e3cfd5e340b4e1063f69e9641978d37e19dd3 100644
--- a/third_party/WebKit/Source/core/input/TouchEventManager.cpp
+++ b/third_party/WebKit/Source/core/input/TouchEventManager.cpp
@@ -37,19 +37,17 @@ bool HasTouchHandlers(const EventHandlerRegistry& registry) {
              EventHandlerRegistry::kTouchEndOrCancelEventPassive);
 }
 
-const AtomicString& TouchEventNameForTouchPointState(
-    WebTouchPoint::State state) {
-  switch (state) {
-    case WebTouchPoint::kStateReleased:
+const AtomicString& TouchEventNameForPointerEventType(
+    WebInputEvent::Type type) {
+  switch (type) {
+    case WebInputEvent::kPointerUp:
       return EventTypeNames::touchend;
-    case WebTouchPoint::kStateCancelled:
+    case WebInputEvent::kPointerCancel:
       return EventTypeNames::touchcancel;
-    case WebTouchPoint::kStatePressed:
+    case WebInputEvent::kPointerDown:
       return EventTypeNames::touchstart;
-    case WebTouchPoint::kStateMoved:
+    case WebInputEvent::kPointerMove:
       return EventTypeNames::touchmove;
-    case WebTouchPoint::kStateStationary:
-    // Fall through to default
     default:
       NOTREACHED();
       return g_empty_atom;
@@ -62,19 +60,55 @@ enum TouchEventDispatchResultType {
   kTouchEventDispatchResultTypeMax,
 };
 
-bool IsTouchSequenceStart(const WebTouchEvent& event) {
-  if (!event.touches_length)
-    return false;
-  if (event.GetType() != WebInputEvent::kTouchStart)
-    return false;
-  for (size_t i = 0; i < event.touches_length; ++i) {
-    if (event.touches[i].state != blink::WebTouchPoint::kStatePressed)
-      return false;
+WebTouchPoint::State TouchPointStateFromPointerEventType(
+    WebInputEvent::Type type,
+    bool stale) {
+  if (stale)
+    return WebTouchPoint::kStateStationary;
+  switch (type) {
+    case WebInputEvent::Type::kPointerUp:
+      return WebTouchPoint::kStateReleased;
+    case WebInputEvent::Type::kPointerCancel:
+      return WebTouchPoint::kStateCancelled;
+    case WebInputEvent::Type::kPointerDown:
+      return WebTouchPoint::kStatePressed;
+    case WebInputEvent::Type::kPointerMove:
+      return WebTouchPoint::kStateMoved;
+    default:
+      NOTREACHED();
+      return WebTouchPoint::kStateUndefined;
   }
-  return true;
 }
 
-// Defining this class type local to dispatchTouchEvents() and annotating
+WebTouchPoint CreateWebTouchPointFromWebPointerEvent(
+    const WebPointerEvent& web_pointer_event,
+    bool stale) {
+  WebTouchPoint web_touch_point(web_pointer_event);
+  web_touch_point.state =
+      TouchPointStateFromPointerEventType(web_pointer_event.GetType(), stale);
+  // TODO(crbug.com/731725): This mapping needs a division by 2.
+  web_touch_point.radius_x = web_pointer_event.width;
+  web_touch_point.radius_y = web_pointer_event.height;
+  web_touch_point.rotation_angle = web_pointer_event.rotation_angle;
+  return web_touch_point;
+}
+
+void SetWebTouchEventAttributesFromWebPointerEvent(
+    WebTouchEvent* web_touch_event,
+    const WebPointerEvent& web_pointer_event) {
+  web_touch_event->dispatch_type = web_pointer_event.dispatch_type;
+  web_touch_event->touch_start_or_first_touch_move =
+      web_pointer_event.touch_start_or_first_touch_move;
+  web_touch_event->moved_beyond_slop_region =
+      web_pointer_event.moved_beyond_slop_region;
+  web_touch_event->SetFrameScale(web_pointer_event.FrameScale());
+  web_touch_event->SetFrameTranslate(web_pointer_event.FrameTranslate());
+  web_touch_event->SetTimeStampSeconds(web_pointer_event.TimeStampSeconds());
+  web_touch_event->SetModifiers(web_pointer_event.GetModifiers());
+}
+
+// Defining this class type local to
+// DispatchTouchEventFromAccumulatdTouchPoints() and annotating
 // it with STACK_ALLOCATED(), runs into MSVC(VS 2013)'s C4822 warning
 // that the local class doesn't provide a local definition for 'operator new'.
 // Which it intentionally doesn't and shouldn't.
@@ -92,10 +126,70 @@ class ChangedTouches final {
   using EventTargetSet = HeapHashSet<Member<EventTarget>>;
   // Set of targets involved in m_touches.
   EventTargetSet targets_;
-
-  WebPointerProperties::PointerType pointer_type_;
 };
 
+void ReportMetricsForTouch(const WebPointerEvent& event,
+                           DispatchEventResult dom_dispatch_result,
+                           bool prevent_default_called_on_uncancelable_event,
+                           bool is_frame_loaded) {
+  int64_t latency_in_micros =
+      (TimeTicks::Now() - TimeTicks::FromSeconds(event.TimeStampSeconds()))
+          .InMicroseconds();
+  if (event.IsCancelable()) {
+    if (is_frame_loaded) {
+      DEFINE_STATIC_LOCAL(EnumerationHistogram,
+                          touch_dispositions_after_page_load_histogram,
+                          ("Event.Touch.TouchDispositionsAfterPageLoad",
+                           kTouchEventDispatchResultTypeMax));
+      touch_dispositions_after_page_load_histogram.Count(
+          (dom_dispatch_result != DispatchEventResult::kNotCanceled)
+              ? kHandledTouches
+              : kUnhandledTouches);
+
+      DEFINE_STATIC_LOCAL(
+          CustomCountHistogram, event_latency_after_page_load_histogram,
+          ("Event.Touch.TouchLatencyAfterPageLoad", 1, 100000000, 50));
+      event_latency_after_page_load_histogram.Count(latency_in_micros);
+    } else {
+      DEFINE_STATIC_LOCAL(EnumerationHistogram,
+                          touch_dispositions_before_page_load_histogram,
+                          ("Event.Touch.TouchDispositionsBeforePageLoad",
+                           kTouchEventDispatchResultTypeMax));
+      touch_dispositions_before_page_load_histogram.Count(
+          (dom_dispatch_result != DispatchEventResult::kNotCanceled)
+              ? kHandledTouches
+              : kUnhandledTouches);
+
+      DEFINE_STATIC_LOCAL(
+          CustomCountHistogram, event_latency_before_page_load_histogram,
+          ("Event.Touch.TouchLatencyBeforePageLoad", 1, 100000000, 50));
+      event_latency_before_page_load_histogram.Count(latency_in_micros);
+    }
+    // Report the touch disposition there is no active fling animation.
+    DEFINE_STATIC_LOCAL(EnumerationHistogram,
+                        touch_dispositions_outside_fling_histogram,
+                        ("Event.Touch.TouchDispositionsOutsideFling2",
+                         kTouchEventDispatchResultTypeMax));
+    touch_dispositions_outside_fling_histogram.Count(
+        (dom_dispatch_result != DispatchEventResult::kNotCanceled)
+            ? kHandledTouches
+            : kUnhandledTouches);
+  }
+
+  // Report the touch disposition when there is an active fling
+  // animation.
+  if (event.dispatch_type ==
+      WebInputEvent::kListenersForcedNonBlockingDueToFling) {
+    DEFINE_STATIC_LOCAL(EnumerationHistogram,
+                        touch_dispositions_during_fling_histogram,
+                        ("Event.Touch.TouchDispositionsDuringFling2",
+                         kTouchEventDispatchResultTypeMax));
+    touch_dispositions_during_fling_histogram.Count(
+        prevent_default_called_on_uncancelable_event ? kHandledTouches
+                                                     : kUnhandledTouches);
+  }
+}
+
 }  // namespace
 
 TouchEventManager::TouchEventManager(LocalFrame& frame) : frame_(frame) {
@@ -104,9 +198,8 @@ TouchEventManager::TouchEventManager(LocalFrame& frame) : frame_(frame) {
 
 void TouchEventManager::Clear() {
   touch_sequence_document_.Clear();
-  target_for_touch_id_.clear();
-  region_for_touch_id_.clear();
-  touch_pressed_ = false;
+  touch_attribute_map_.clear();
+  last_coalesced_touch_event_ = WebTouchEvent();
   suppressing_touchmoves_within_slop_ = false;
   current_touch_action_ = TouchAction::kTouchActionAuto;
 }
@@ -114,31 +207,18 @@ void TouchEventManager::Clear() {
 DEFINE_TRACE(TouchEventManager) {
   visitor->Trace(frame_);
   visitor->Trace(touch_sequence_document_);
-  visitor->Trace(target_for_touch_id_);
+  visitor->Trace(touch_attribute_map_);
 }
 
-Touch* TouchEventManager::CreateDomTouch(const WebTouchPoint& point,
-                                         bool* known_target) {
-  Node* touch_node = nullptr;
-  String region_id;
+Touch* TouchEventManager::CreateDomTouch(
+    const TouchEventManager::TouchPointAttributes* point_attr,
+    bool* known_target) {
+  Node* touch_node = point_attr->target_;
+  String region_id = point_attr->region_;
   *known_target = false;
   FloatPoint content_point;
   FloatSize adjusted_radius;
 
-  if (point.state == WebTouchPoint::kStateReleased ||
-      point.state == WebTouchPoint::kStateCancelled) {
-    // The target should be the original target for this touch, so get
-    // it from the hashmap. As it's a release or cancel we also remove
-    // it from the map.
-    touch_node = target_for_touch_id_.Take(point.id);
-    region_id = region_for_touch_id_.Take(point.id);
-  } else {
-    // No hittest is performed on move or stationary, since the target
-    // is not allowed to change anyway.
-    touch_node = target_for_touch_id_.at(point.id);
-    region_id = region_for_touch_id_.at(point.id);
-  }
-
   LocalFrame* target_frame = nullptr;
   if (touch_node) {
     Document& doc = touch_node->GetDocument();
@@ -169,40 +249,193 @@ Touch* TouchEventManager::CreateDomTouch(const WebTouchPoint& point,
   }
   DCHECK(target_frame);
 
+  WebPointerEvent transformed_event =
+      point_attr->event_.WebPointerEventInRootFrame();
   // pagePoint should always be in the target element's document coordinates.
-  FloatPoint page_point =
-      target_frame->View()->RootFrameToContents(point.PositionInWidget());
+  FloatPoint page_point = target_frame->View()->RootFrameToContents(
+      transformed_event.PositionInWidget());
   float scale_factor = 1.0f / target_frame->PageZoomFactor();
 
   content_point = page_point.ScaledBy(scale_factor);
-  adjusted_radius =
-      FloatSize(point.radius_x, point.radius_y).ScaledBy(scale_factor);
+  adjusted_radius = FloatSize(transformed_event.width, transformed_event.height)
+                        .ScaledBy(scale_factor);
+
+  return Touch::Create(target_frame, touch_node, point_attr->event_.id,
+                       transformed_event.PositionInScreen(), content_point,
+                       adjusted_radius, transformed_event.rotation_angle,
+                       transformed_event.force, region_id);
+}
+
+WebCoalescedInputEvent TouchEventManager::GenerateWebCoalescedInputEvent() {
+  DCHECK(!touch_attribute_map_.IsEmpty());
+
+  WebTouchEvent event;
+
+  const auto& first_touch_pointer_event =
+      touch_attribute_map_.begin()->value->event_;
+
+  SetWebTouchEventAttributesFromWebPointerEvent(&event,
+                                                first_touch_pointer_event);
+  SetWebTouchEventAttributesFromWebPointerEvent(&last_coalesced_touch_event_,
+                                                first_touch_pointer_event);
+  WebInputEvent::Type touch_event_type = WebInputEvent::kTouchMove;
+  Vector<WebPointerEvent> all_coalesced_events;
+  Vector<int> available_ids;
+  for (const auto& id : touch_attribute_map_.Keys())
+    available_ids.push_back(id);
+  std::sort(available_ids.begin(), available_ids.end());
+  for (const int& touch_point_id : available_ids) {
+    const auto& touch_point_attribute = touch_attribute_map_.at(touch_point_id);
+    const WebPointerEvent& touch_pointer_event = touch_point_attribute->event_;
+    event.touches[event.touches_length++] =
+        CreateWebTouchPointFromWebPointerEvent(touch_pointer_event,
+                                               touch_point_attribute->stale_);
+
+    // Only change the touch event type from move. So if we have two pointers
+    // in up and down state we just set the touch event type to the first one
+    // we see.
+    // TODO(crbug.com/732842): Note that event sender API allows sending any
+    // mix of input and as long as we don't crash or anything we should be good
+    // for now.
+    if (touch_event_type == WebInputEvent::kTouchMove) {
+      if (touch_pointer_event.GetType() == WebInputEvent::kPointerDown)
+        touch_event_type = WebInputEvent::kTouchStart;
+      else if (touch_pointer_event.GetType() == WebInputEvent::kPointerCancel)
+        touch_event_type = WebInputEvent::kTouchCancel;
+      else if (touch_pointer_event.GetType() == WebInputEvent::kPointerUp)
+        touch_event_type = WebInputEvent::kTouchEnd;
+    }
+
+    for (const WebPointerEvent& coalesced_event :
+         touch_point_attribute->coalesced_events_) {
+      all_coalesced_events.push_back(coalesced_event);
+    }
+  }
+  event.SetType(touch_event_type);
+  last_coalesced_touch_event_.SetType(touch_event_type);
 
-  return Touch::Create(target_frame, touch_node, point.id,
-                       point.PositionInScreen(), content_point, adjusted_radius,
-                       point.rotation_angle, point.force, region_id);
+  // Create all coalesced touch events based on pointerevents
+  struct {
+    bool operator()(const WebPointerEvent& a, const WebPointerEvent& b) {
+      return a.TimeStampSeconds() < b.TimeStampSeconds();
+    }
+  } timestamp_based_event_comparison;
+  std::sort(all_coalesced_events.begin(), all_coalesced_events.end(),
+            timestamp_based_event_comparison);
+  WebCoalescedInputEvent result(event, std::vector<const WebInputEvent*>());
+  for (const auto& web_pointer_event : all_coalesced_events) {
+    if (web_pointer_event.GetType() == WebInputEvent::kPointerDown) {
+      // TODO(crbug.com/732842): Technically we should never receive the
+      // pointerdown twice for the same touch point. But event sender API allows
+      // that. So we should handle it gracefully.
+      WebTouchPoint web_touch_point(web_pointer_event);
+      bool found_existing_id = false;
+      for (unsigned i = 0; i < last_coalesced_touch_event_.touches_length;
+           ++i) {
+        if (last_coalesced_touch_event_.touches[i].id == web_pointer_event.id) {
+          last_coalesced_touch_event_.touches[i] =
+              CreateWebTouchPointFromWebPointerEvent(web_pointer_event, false);
+          found_existing_id = true;
+          break;
+        }
+      }
+      // If the pointerdown point didn't exist add a new point to the array.
+      if (!found_existing_id) {
+        last_coalesced_touch_event_
+            .touches[last_coalesced_touch_event_.touches_length++] =
+            CreateWebTouchPointFromWebPointerEvent(web_pointer_event, false);
+      }
+      struct {
+        bool operator()(const WebTouchPoint& a, const WebTouchPoint& b) {
+          return a.id < b.id;
+        }
+      } id_based_event_comparison;
+      std::sort(last_coalesced_touch_event_.touches,
+                last_coalesced_touch_event_.touches +
+                    last_coalesced_touch_event_.touches_length,
+                id_based_event_comparison);
+      result.AddCoalescedEvent(last_coalesced_touch_event_);
+    } else {
+      for (unsigned i = 0; i < last_coalesced_touch_event_.touches_length;
+           ++i) {
+        if (last_coalesced_touch_event_.touches[i].id == web_pointer_event.id) {
+          last_coalesced_touch_event_.touches[i].movement_x =
+              web_pointer_event.movement_x;
+          last_coalesced_touch_event_.touches[i].movement_y =
+              web_pointer_event.movement_y;
+          last_coalesced_touch_event_.SetTimeStampSeconds(
+              web_pointer_event.TimeStampSeconds());
+          last_coalesced_touch_event_.touches[i].state =
+              TouchPointStateFromPointerEventType(web_pointer_event.GetType(),
+                                                  false);
+          result.AddCoalescedEvent(last_coalesced_touch_event_);
+
+          // Remove up and canceled points.
+          unsigned result_size = 0;
+          for (unsigned j = 0; j < last_coalesced_touch_event_.touches_length;
+               j++) {
+            if (last_coalesced_touch_event_.touches[j].state !=
+                    WebTouchPoint::kStateCancelled &&
+                last_coalesced_touch_event_.touches[j].state !=
+                    WebTouchPoint::kStateReleased) {
+              last_coalesced_touch_event_.touches[result_size++] =
+                  last_coalesced_touch_event_.touches[j];
+            }
+          }
+          last_coalesced_touch_event_.touches_length = result_size;
+          break;
+        }
+      }
+    }
+
+    for (unsigned i = 0; i < event.touches_length; ++i) {
+      event.touches[i].state = blink::WebTouchPoint::kStateStationary;
+      event.touches[i].movement_x = 0;
+      event.touches[i].movement_y = 0;
+    }
+  }
+
+  return result;
 }
 
-WebInputEventResult TouchEventManager::DispatchTouchEvents(
-    const WebTouchEvent& event,
-    const Vector<WebTouchEvent>& coalesced_events,
-    bool all_touches_released) {
+WebInputEventResult
+TouchEventManager::DispatchTouchEventFromAccumulatdTouchPoints() {
   // Build up the lists to use for the |touches|, |targetTouches| and
   // |changedTouches| attributes in the JS event. See
   // http://www.w3.org/TR/touch-events/#touchevent-interface for how these
   // lists fit together.
 
-  if (event.GetType() == WebInputEvent::kTouchEnd ||
-      event.GetType() == WebInputEvent::kTouchCancel ||
-      event.touches_length > 1) {
-    suppressing_touchmoves_within_slop_ = false;
+  bool new_touch_point_since_last_dispatch = false;
+  bool any_touch_canceled_or_ended = false;
+  bool all_touch_points_pressed = true;
+
+  for (const auto& attr : touch_attribute_map_.Values()) {
+    if (!attr->stale_)
+      new_touch_point_since_last_dispatch = true;
+    if (attr->event_.GetType() == WebInputEvent::kPointerUp ||
+        attr->event_.GetType() == WebInputEvent::kPointerCancel)
+      any_touch_canceled_or_ended = true;
+    if (attr->event_.GetType() != WebInputEvent::kPointerDown)
+      all_touch_points_pressed = false;
   }
 
-  if (suppressing_touchmoves_within_slop_ &&
-      event.GetType() == WebInputEvent::kTouchMove) {
-    if (!event.moved_beyond_slop_region)
-      return WebInputEventResult::kHandledSuppressed;
+  if (!new_touch_point_since_last_dispatch)
+    return WebInputEventResult::kNotHandled;
+
+  if (any_touch_canceled_or_ended || touch_attribute_map_.size() > 1)
     suppressing_touchmoves_within_slop_ = false;
+
+  if (suppressing_touchmoves_within_slop_) {
+    // There is exactly one touch point here otherwise
+    // |suppressing_touchmoves_within_slop_| would have been false.
+    DCHECK_EQ(1U, touch_attribute_map_.size());
+    const auto& touch_point_attribute = touch_attribute_map_.begin()->value;
+    if (touch_point_attribute->event_.GetType() ==
+        WebInputEvent::kPointerMove) {
+      if (!touch_point_attribute->event_.moved_beyond_slop_region)
+        return WebInputEventResult::kHandledSuppressed;
+      suppressing_touchmoves_within_slop_ = false;
+    }
   }
 
   // Holds the complete set of touches on the screen.
@@ -214,15 +447,19 @@ WebInputEventResult TouchEventManager::DispatchTouchEvents(
   TargetTouchesHeapMap touches_by_target;
 
   // Array of touches per state, used to assemble the |changedTouches| list.
-  ChangedTouches changed_touches[WebTouchPoint::kStateMax + 1];
-
-  for (unsigned touch_point_idx = 0; touch_point_idx < event.touches_length;
-       touch_point_idx++) {
-    const WebTouchPoint& point = event.TouchPointInRootFrame(touch_point_idx);
-    WebTouchPoint::State point_state = point.state;
+  ChangedTouches changed_touches[WebInputEvent::kPointerTypeLast -
+                                 WebInputEvent::kPointerTypeFirst + 1];
+
+  Vector<int> available_ids;
+  for (const auto& id : touch_attribute_map_.Keys())
+    available_ids.push_back(id);
+  std::sort(available_ids.begin(), available_ids.end());
+  for (const int& touch_point_id : available_ids) {
+    const auto& touch_point_attribute = touch_attribute_map_.at(touch_point_id);
+    WebInputEvent::Type event_type = touch_point_attribute->event_.GetType();
     bool known_target;
 
-    Touch* touch = CreateDomTouch(point, &known_target);
+    Touch* touch = CreateDomTouch(touch_point_attribute, &known_target);
     EventTarget* touch_target = touch->target();
 
     // Ensure this target's touch list exists, even if it ends up empty, so
@@ -237,8 +474,8 @@ WebInputEventResult TouchEventManager::DispatchTouchEvents(
     // |touches| and |targetTouches| should only contain information about
     // touches still on the screen, so if this point is released or
     // cancelled it will only appear in the |changedTouches| list.
-    if (point_state != WebTouchPoint::kStateReleased &&
-        point_state != WebTouchPoint::kStateCancelled) {
+    if (event_type != WebInputEvent::kPointerUp &&
+        event_type != WebInputEvent::kPointerCancel) {
       touches->Append(touch);
       target_touches_iterator->value->Append(touch);
     }
@@ -249,43 +486,37 @@ WebInputEventResult TouchEventManager::DispatchTouchEvents(
     // never be in the |changedTouches| list so we do not handle them
     // explicitly here. See https://bugs.webkit.org/show_bug.cgi?id=37609
     // for further discussion about the TouchStationary state.
-    if (point_state != WebTouchPoint::kStateStationary && known_target) {
-      DCHECK_LE(point_state, WebTouchPoint::kStateMax);
-      if (!changed_touches[point_state].touches_)
-        changed_touches[point_state].touches_ = TouchList::Create();
-      changed_touches[point_state].touches_->Append(touch);
-      changed_touches[point_state].targets_.insert(touch_target);
-      changed_touches[point_state].pointer_type_ = point.pointer_type;
+    if (!touch_point_attribute->stale_ && known_target) {
+      size_t event_type_idx = event_type - WebInputEvent::kPointerTypeFirst;
+      if (!changed_touches[event_type_idx].touches_)
+        changed_touches[event_type_idx].touches_ = TouchList::Create();
+      changed_touches[event_type_idx].touches_->Append(touch);
+      changed_touches[event_type_idx].targets_.insert(touch_target);
     }
   }
 
-  if (all_touches_released) {
-    touch_sequence_document_.Clear();
-    current_touch_action_ = TouchAction::kTouchActionAuto;
-  }
-
   WebInputEventResult event_result = WebInputEventResult::kNotHandled;
-  // First we construct the webcoalescedinputevent contains all the coalesced
+
+  // First we construct the webcoalescedinputevent containing all the coalesced
   // touch event.
-  std::vector<const WebInputEvent*> coalesced_touches;
-  for (size_t i = 0; i < coalesced_events.size(); ++i) {
-    coalesced_touches.push_back(&coalesced_events[i]);
-  }
-  WebCoalescedInputEvent coalesced_event(event, coalesced_touches);
+  WebCoalescedInputEvent coalesced_event = GenerateWebCoalescedInputEvent();
 
   // Now iterate through the |changedTouches| list and |m_targets| within it,
   // sending TouchEvents to the targets as required.
-  for (unsigned state = 0; state <= WebTouchPoint::kStateMax; ++state) {
-    if (!changed_touches[state].touches_)
+  for (unsigned action = WebInputEvent::kPointerTypeFirst;
+       action <= WebInputEvent::kPointerTypeLast; ++action) {
+    size_t action_idx = action - WebInputEvent::kPointerTypeFirst;
+    if (!changed_touches[action_idx].touches_)
       continue;
 
-    const AtomicString& event_name(TouchEventNameForTouchPointState(
-        static_cast<WebTouchPoint::State>(state)));
-    for (const auto& event_target : changed_touches[state].targets_) {
+    const AtomicString& event_name(TouchEventNameForPointerEventType(
+        static_cast<WebInputEvent::Type>(action)));
+
+    for (const auto& event_target : changed_touches[action_idx].targets_) {
       EventTarget* touch_event_target = event_target;
       TouchEvent* touch_event = TouchEvent::Create(
           coalesced_event, touches, touches_by_target.at(touch_event_target),
-          changed_touches[state].touches_.Get(), event_name,
+          changed_touches[action_idx].touches_.Get(), event_name,
           touch_event_target->ToNode()->GetDocument().domWindow(),
           current_touch_action_);
 
@@ -294,66 +525,15 @@ WebInputEventResult TouchEventManager::DispatchTouchEvents(
 
       // Only report for top level documents with a single touch on
       // touch-start or the first touch-move.
-      if (event.touch_start_or_first_touch_move && event.touches_length == 1 &&
-          frame_->IsMainFrame()) {
-        // Record the disposition and latency of touch starts and first touch
-        // moves before and after the page is fully loaded respectively.
-        int64_t latency_in_micros =
-            (TimeTicks::Now() -
-             TimeTicks::FromSeconds(event.TimeStampSeconds()))
-                .InMicroseconds();
-        if (event.IsCancelable()) {
-          if (frame_->GetDocument()->IsLoadCompleted()) {
-            DEFINE_STATIC_LOCAL(EnumerationHistogram,
-                                touch_dispositions_after_page_load_histogram,
-                                ("Event.Touch.TouchDispositionsAfterPageLoad",
-                                 kTouchEventDispatchResultTypeMax));
-            touch_dispositions_after_page_load_histogram.Count(
-                (dom_dispatch_result != DispatchEventResult::kNotCanceled)
-                    ? kHandledTouches
-                    : kUnhandledTouches);
-
-            DEFINE_STATIC_LOCAL(
-                CustomCountHistogram, event_latency_after_page_load_histogram,
-                ("Event.Touch.TouchLatencyAfterPageLoad", 1, 100000000, 50));
-            event_latency_after_page_load_histogram.Count(latency_in_micros);
-          } else {
-            DEFINE_STATIC_LOCAL(EnumerationHistogram,
-                                touch_dispositions_before_page_load_histogram,
-                                ("Event.Touch.TouchDispositionsBeforePageLoad",
-                                 kTouchEventDispatchResultTypeMax));
-            touch_dispositions_before_page_load_histogram.Count(
-                (dom_dispatch_result != DispatchEventResult::kNotCanceled)
-                    ? kHandledTouches
-                    : kUnhandledTouches);
-
-            DEFINE_STATIC_LOCAL(
-                CustomCountHistogram, event_latency_before_page_load_histogram,
-                ("Event.Touch.TouchLatencyBeforePageLoad", 1, 100000000, 50));
-            event_latency_before_page_load_histogram.Count(latency_in_micros);
-          }
-          // Report the touch disposition there is no active fling animation.
-          DEFINE_STATIC_LOCAL(EnumerationHistogram,
-                              touch_dispositions_outside_fling_histogram,
-                              ("Event.Touch.TouchDispositionsOutsideFling2",
-                               kTouchEventDispatchResultTypeMax));
-          touch_dispositions_outside_fling_histogram.Count(
-              (dom_dispatch_result != DispatchEventResult::kNotCanceled)
-                  ? kHandledTouches
-                  : kUnhandledTouches);
-        }
-
-        // Report the touch disposition when there is an active fling animation.
-        if (event.dispatch_type ==
-            WebInputEvent::kListenersForcedNonBlockingDueToFling) {
-          DEFINE_STATIC_LOCAL(EnumerationHistogram,
-                              touch_dispositions_during_fling_histogram,
-                              ("Event.Touch.TouchDispositionsDuringFling2",
-                               kTouchEventDispatchResultTypeMax));
-          touch_dispositions_during_fling_histogram.Count(
-              touch_event->PreventDefaultCalledOnUncancelableEvent()
-                  ? kHandledTouches
-                  : kUnhandledTouches);
+      if (touch_attribute_map_.size() == 1 && frame_->IsMainFrame()) {
+        const auto& event = touch_attribute_map_.begin()->value->event_;
+        if (event.touch_start_or_first_touch_move) {
+          // Record the disposition and latency of touch starts and first touch
+          // moves before and after the page is fully loaded respectively.
+          ReportMetricsForTouch(
+              event, dom_dispatch_result,
+              touch_event->PreventDefaultCalledOnUncancelableEvent(),
+              frame_->GetDocument()->IsLoadCompleted());
         }
       }
       event_result = EventHandlingUtil::MergeEventResult(
@@ -362,8 +542,9 @@ WebInputEventResult TouchEventManager::DispatchTouchEvents(
     }
   }
 
-  // Do not suppress any touchmoves if the touchstart is consumed.
-  if (IsTouchSequenceStart(event) &&
+  // Suppress following touchmoves within the slop region if the touchstart is
+  // not consumed.
+  if (all_touch_points_pressed &&
       event_result == WebInputEventResult::kNotHandled) {
     suppressing_touchmoves_within_slop_ = true;
   }
@@ -371,14 +552,22 @@ WebInputEventResult TouchEventManager::DispatchTouchEvents(
   return event_result;
 }
 
-void TouchEventManager::UpdateTargetAndRegionMapsForTouchStart(
-    const WebTouchPoint& touch_point,
+void TouchEventManager::UpdateTouchAttributeMapsForPointerDown(
+    const WebPointerEvent& event,
     const EventHandlingUtil::PointerEventTarget& pointer_event_target) {
   // Touch events implicitly capture to the touched node, and don't change
   // active/hover states themselves (Gesture events do). So we only need
   // to hit-test on touchstart and when the target could be different than
   // the corresponding pointer event target.
-  DCHECK(touch_point.state == WebTouchPoint::kStatePressed);
+  DCHECK(event.GetType() == WebInputEvent::kPointerDown);
+  // Ideally we'd DCHECK(!touch_attribute_map_.Contains(event.id))
+  // since we shouldn't get a touchstart for a touch that's already
+  // down. However EventSender allows this to be violated and there's
+  // some tests that take advantage of it. There may also be edge
+  // cases in the browser where this happens.
+  // See http://crbug.com/345372.
+  touch_attribute_map_.Set(event.id, new TouchPointAttributes(event));
+
   Node* touch_node = pointer_event_target.target_node;
   String region = pointer_event_target.region;
 
@@ -398,7 +587,7 @@ void TouchEventManager::UpdateTargetAndRegionMapsForTouchStart(
     if (touch_sequence_document_->GetFrame()) {
       LayoutPoint frame_point = LayoutPoint(
           touch_sequence_document_->GetFrame()->View()->RootFrameToContents(
-              touch_point.PositionInWidget()));
+              event.PositionInWidget()));
       result = EventHandlingUtil::HitTestResultInFrame(
           touch_sequence_document_->GetFrame(), frame_point, hit_type);
       Node* node = result.InnerNode();
@@ -430,15 +619,9 @@ void TouchEventManager::UpdateTargetAndRegionMapsForTouchStart(
     DCHECK(touch_sequence_document_->GetFrame()->View());
   }
 
-  // Ideally we'd DCHECK(!m_targetForTouchID.contains(point.id())
-  // since we shouldn't get a touchstart for a touch that's already
-  // down. However EventSender allows this to be violated and there's
-  // some tests that take advantage of it. There may also be edge
-  // cases in the browser where this happens.
-  // See http://crbug.com/345372.
-  target_for_touch_id_.Set(touch_point.id, touch_node);
-
-  region_for_touch_id_.Set(touch_point.id, region);
+  TouchPointAttributes* attributes = touch_attribute_map_.at(event.id);
+  attributes->target_ = touch_node;
+  attributes->region_ = region;
 
   TouchAction effective_touch_action =
       TouchActionUtil::ComputeEffectiveTouchAction(*touch_node);
@@ -452,28 +635,20 @@ void TouchEventManager::UpdateTargetAndRegionMapsForTouchStart(
   }
 }
 
-bool TouchEventManager::HitTestTouchPointsIfNeeded(
-    const WebTouchEvent& event,
-    const HeapVector<EventHandlingUtil::PointerEventTarget>&
-        pointer_event_targets) {
-  bool new_touch_sequence = true;
-  bool all_touches_released = true;
-
-  for (unsigned i = 0; i < event.touches_length; ++i) {
-    WebTouchPoint::State state = event.touches[i].state;
-    if (state != WebTouchPoint::kStatePressed)
-      new_touch_sequence = false;
-    if (state != WebTouchPoint::kStateReleased &&
-        state != WebTouchPoint::kStateCancelled)
-      all_touches_released = false;
-  }
-  if (new_touch_sequence) {
+void TouchEventManager::HandleTouchPoint(
+    const WebPointerEvent& event,
+    const Vector<WebPointerEvent>& coalesced_events,
+    const EventHandlingUtil::PointerEventTarget& pointer_event_target) {
+  DCHECK_GE(event.GetType(), WebInputEvent::kPointerTypeFirst);
+  DCHECK_LE(event.GetType(), WebInputEvent::kPointerTypeLast);
+
+  if (touch_attribute_map_.IsEmpty()) {
     // Ideally we'd DCHECK(!m_touchSequenceDocument) here since we should
     // have cleared the active document when we saw the last release. But we
     // have some tests that violate this, ClusterFuzz could trigger it, and
     // there may be cases where the browser doesn't reliably release all
     // touches. http://crbug.com/345372 tracks this.
-    touch_sequence_document_.Clear();
+    AllTouchesReleasedCleanup();
   }
 
   DCHECK(frame_->View());
@@ -482,59 +657,74 @@ bool TouchEventManager::HitTestTouchPointsIfNeeded(
        !touch_sequence_document_->GetFrame()->View())) {
     // If the active touch document has no frame or view, it's probably being
     // destroyed so we can't dispatch events.
-    return false;
+    return;
   }
 
-  for (unsigned i = 0; i < event.touches_length; ++i) {
-    // In touch event model only touch starts can set the target and after that
-    // the touch event always goes to that target.
-    if (event.touches[i].state == WebTouchPoint::kStatePressed) {
-      UpdateTargetAndRegionMapsForTouchStart(event.TouchPointInRootFrame(i),
-                                             pointer_event_targets[i]);
-    }
+  // In touch event model only touch starts can set the target and after that
+  // the touch event always goes to that target.
+  if (event.GetType() == WebInputEvent::kPointerDown) {
+    UpdateTouchAttributeMapsForPointerDown(event, pointer_event_target);
   }
 
-  touch_pressed_ = !all_touches_released;
-
-  // If there's no document receiving touch events, or no handlers on the
-  // document set to receive the events, then we can skip all the rest of
-  // this work.
-  if (!touch_sequence_document_ || !touch_sequence_document_->GetPage() ||
-      !HasTouchHandlers(
-          touch_sequence_document_->GetPage()->GetEventHandlerRegistry()) ||
-      !touch_sequence_document_->GetFrame()) {
-    if (all_touches_released) {
-      touch_sequence_document_.Clear();
-    }
-    return false;
+  // We might not receive the down action for a touch point. In that case we
+  // would have never added them to |touch_attribute_map_| or hit-tested
+  // them. For those just keep them in the map with a null target. Later they
+  // will be targeted at the |touch_sequence_document_|.
+  if (!touch_attribute_map_.Contains(event.id)) {
+    touch_attribute_map_.insert(event.id, new TouchPointAttributes(event));
   }
 
-  return true;
+  TouchPointAttributes* attributes = touch_attribute_map_.at(event.id);
+  attributes->event_ = event;
+  attributes->coalesced_events_ = coalesced_events;
+  attributes->stale_ = false;
 }
 
-WebInputEventResult TouchEventManager::HandleTouchEvent(
-    const WebTouchEvent& event,
-    const Vector<WebTouchEvent>& coalesced_events,
-    const HeapVector<EventHandlingUtil::PointerEventTarget>&
-        pointer_event_targets) {
-  DCHECK(event.touches_length == pointer_event_targets.size());
+WebInputEventResult TouchEventManager::FlushEvents() {
+  WebInputEventResult result = WebInputEventResult::kNotHandled;
 
-  if (!HitTestTouchPointsIfNeeded(event, pointer_event_targets))
-    return WebInputEventResult::kNotHandled;
+  // If there's no document receiving touch events, or no handlers on the
+  // document set to receive the events, then we can skip all the rest of
+  // sending the event.
+  if (touch_sequence_document_ && touch_sequence_document_->GetPage() &&
+      HasTouchHandlers(
+          touch_sequence_document_->GetPage()->GetEventHandlerRegistry()) &&
+      touch_sequence_document_->GetFrame() &&
+      touch_sequence_document_->GetFrame()->View()) {
+    result = DispatchTouchEventFromAccumulatdTouchPoints();
+  }
+
+  // Cleanup the |touch_attribute_map_| map from released and canceled
+  // touch points.
+  Vector<int> released_canceled_points;
+  for (auto& attributes : touch_attribute_map_.Values()) {
+    if (attributes->event_.GetType() == WebInputEvent::kPointerUp ||
+        attributes->event_.GetType() == WebInputEvent::kPointerCancel) {
+      released_canceled_points.push_back(attributes->event_.id);
+    } else {
+      attributes->stale_ = true;
+      attributes->event_.movement_x = 0;
+      attributes->event_.movement_y = 0;
+      attributes->coalesced_events_.clear();
+    }
+  }
+  touch_attribute_map_.RemoveAll(released_canceled_points);
 
-  bool all_touches_released = true;
-  for (unsigned i = 0; i < event.touches_length; ++i) {
-    WebTouchPoint::State state = event.touches[i].state;
-    if (state != WebTouchPoint::kStateReleased &&
-        state != WebTouchPoint::kStateCancelled)
-      all_touches_released = false;
+  if (touch_attribute_map_.IsEmpty()) {
+    AllTouchesReleasedCleanup();
   }
 
-  return DispatchTouchEvents(event, coalesced_events, all_touches_released);
+  return result;
+}
+
+void TouchEventManager::AllTouchesReleasedCleanup() {
+  touch_sequence_document_.Clear();
+  current_touch_action_ = TouchAction::kTouchActionAuto;
+  last_coalesced_touch_event_ = WebTouchEvent();
 }
 
 bool TouchEventManager::IsAnyTouchActive() const {
-  return touch_pressed_;
+  return !touch_attribute_map_.IsEmpty();
 }
 
 }  // namespace blink