Notify Blink about start of gesture scroll through a queued event.

components/test_runner/event_sender.cc

Index: components/test_runner/event_sender.cc
diff --git a/components/test_runner/event_sender.cc b/components/test_runner/event_sender.cc
index 31867c91d971bdffbee91640d9c82dac8d67b957..5ad17af1fbdc1c1cb09e7146d30f7ff5292d852c 100644
--- a/components/test_runner/event_sender.cc
+++ b/components/test_runner/event_sender.cc
@@ -20,6 +20,7 @@
 #include "gin/handle.h"
 #include "gin/object_template_builder.h"
 #include "gin/wrappable.h"
+#include "third_party/WebKit/public/platform/WebPointerProperties.h"
 #include "third_party/WebKit/public/platform/WebString.h"
 #include "third_party/WebKit/public/platform/WebVector.h"
 #include "third_party/WebKit/public/web/WebContextMenuData.h"
@@ -45,6 +46,7 @@ using blink::WebMouseEvent;
 using blink::WebMouseWheelEvent;
 using blink::WebPagePopup;
 using blink::WebPoint;
+using blink::WebPointerProperties;
 using blink::WebString;
 using blink::WebTouchEvent;
 using blink::WebTouchPoint;
@@ -494,6 +496,8 @@ class EventSenderBindings : public gin::Wrappable<EventSenderBindings> {
   void TouchMoveCausingScrollIfUncanceled();
   void TouchCancel();
   void TouchEnd();
+  void NotifyStartOfImplScroll();
+  void NotifyEndOfImplScroll();
   void LeapForward(int milliseconds);
   double LastEventTimestamp();
   void BeginDragWithFiles(const std::vector<std::string>& files);
@@ -620,10 +624,12 @@ EventSenderBindings::GetObjectTemplateBuilder(v8::Isolate* isolate) {
                  &EventSenderBindings::GestureScrollFirstPoint)
       .SetMethod("touchStart", &EventSenderBindings::TouchStart)
       .SetMethod("touchMove", &EventSenderBindings::TouchMove)
-      .SetMethod("touchMoveCausingScrollIfUncanceled",
-                 &EventSenderBindings::TouchMoveCausingScrollIfUncanceled)
       .SetMethod("touchCancel", &EventSenderBindings::TouchCancel)
       .SetMethod("touchEnd", &EventSenderBindings::TouchEnd)
+      .SetMethod("notifyStartOfImplScroll",
+                 &EventSenderBindings::NotifyStartOfImplScroll)
+      .SetMethod("notifyEndOfImplScroll",
+                 &EventSenderBindings::NotifyEndOfImplScroll)
       .SetMethod("leapForward", &EventSenderBindings::LeapForward)
       .SetMethod("lastEventTimestamp", &EventSenderBindings::LastEventTimestamp)
       .SetMethod("beginDragWithFiles", &EventSenderBindings::BeginDragWithFiles)
@@ -810,11 +816,6 @@ void EventSenderBindings::TouchMove() {
     sender_->TouchMove();
 }
 
-void EventSenderBindings::TouchMoveCausingScrollIfUncanceled() {
-  if (sender_)
-    sender_->TouchMoveCausingScrollIfUncanceled();
-}
-
 void EventSenderBindings::TouchCancel() {
   if (sender_)
     sender_->TouchCancel();
@@ -825,6 +826,16 @@ void EventSenderBindings::TouchEnd() {
     sender_->TouchEnd();
 }
 
+void EventSenderBindings::NotifyStartOfImplScroll() {
+  if (sender_)
+    sender_->NotifyStartOfImplScroll();
+}
+
+void EventSenderBindings::NotifyEndOfImplScroll() {
+  if (sender_)
+    sender_->NotifyEndOfImplScroll();
+}
+
 void EventSenderBindings::LeapForward(int milliseconds) {
   if (sender_)
     sender_->LeapForward(milliseconds);
@@ -1832,10 +1843,6 @@ void EventSender::TouchMove() {
   SendCurrentTouchEvent(WebInputEvent::TouchMove, false);
 }
 
-void EventSender::TouchMoveCausingScrollIfUncanceled() {
-  SendCurrentTouchEvent(WebInputEvent::TouchMove, true);
-}
-
 void EventSender::TouchCancel() {
   SendCurrentTouchEvent(WebInputEvent::TouchCancel, false);
 }
@@ -1844,6 +1851,20 @@ void EventSender::TouchEnd() {
   SendCurrentTouchEvent(WebInputEvent::TouchEnd, false);
 }
 
+void EventSender::NotifyStartOfImplScroll() {
+  WebGestureEvent gesture_event;
+  gesture_event.type = WebInputEvent::GestureScrollBegin;
+  HandleInputEventOnViewOrPopup(gesture_event,
+                                WebInputEventDispatchType::NonBlocking);
+}
+
+void EventSender::NotifyEndOfImplScroll() {
+  WebGestureEvent gesture_event;
+  gesture_event.type = WebInputEvent::GestureScrollEnd;
+  HandleInputEventOnViewOrPopup(gesture_event,
+                                WebInputEventDispatchType::NonBlocking);
+}
+
 void EventSender::LeapForward(int milliseconds) {
   if (is_drag_mode_ && pressed_button_ == WebMouseEvent::ButtonLeft &&
       !replaying_saved_events_) {