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

third_party/WebKit/LayoutTests/fast/events/pointerevents/touch-pointercancel.html

Index: third_party/WebKit/LayoutTests/fast/events/pointerevents/touch-pointercancel.html
diff --git a/third_party/WebKit/LayoutTests/fast/events/pointerevents/touch-pointercancel.html b/third_party/WebKit/LayoutTests/fast/events/pointerevents/touch-pointercancel.html
index 9b104dd59bdf1b0ae52663b44a3e085e96a214ef..6c0f3e6591aa7d057f795411699a9ca79e27e755 100644
--- a/third_party/WebKit/LayoutTests/fast/events/pointerevents/touch-pointercancel.html
+++ b/third_party/WebKit/LayoutTests/fast/events/pointerevents/touch-pointercancel.html
@@ -61,16 +61,19 @@ function testSingleDrag(uncanceledMoveCausesScroll) {
   eventSender.touchMove();
 
   eventSender.updateTouchPoint(0, x, y+100);
+  eventSender.touchMove();
+
   if (uncanceledMoveCausesScroll)
-    eventSender.touchMoveCausingScrollIfUncanceled();
-  else
-    eventSender.touchMove();
+    eventSender.notifyStartOfImplScroll();
 
   eventSender.updateTouchPoint(0, x, y+150);
   eventSender.touchMove();
 
   eventSender.releaseTouchPoint(0);
   eventSender.touchEnd();
+
+  if (uncanceledMoveCausesScroll)
+    eventSender.notifyEndOfImplScroll();
 }
 
 function testMultiDrag(uncanceledMoveCausesScroll) {
@@ -98,10 +101,10 @@ function testMultiDrag(uncanceledMoveCausesScroll) {
   eventSender.updateTouchPoint(0, x0, y);
   eventSender.updateTouchPoint(1, x1, y);
   eventSender.updateTouchPoint(2, x2, y);
+  eventSender.touchMove();
+
   if (uncanceledMoveCausesScroll)
-    eventSender.touchMoveCausingScrollIfUncanceled();
-  else
-    eventSender.touchMove();
+    eventSender.notifyStartOfImplScroll();
 
   eventSender.addTouchPoint(x3, y);
   eventSender.touchStart();
@@ -118,6 +121,9 @@ function testMultiDrag(uncanceledMoveCausesScroll) {
   eventSender.releaseTouchPoint(2);
   eventSender.releaseTouchPoint(3);
   eventSender.touchEnd();
+
+  if (uncanceledMoveCausesScroll)
+    eventSender.notifyEndOfImplScroll();
 }
 
 function testMultiCancel() {
@@ -161,6 +167,8 @@ function runTests() {
   testSingleDrag(false);
   debug("");
 
+  // TODO(mustaq): Scrolling is now independent of whether the TEs sent thru eventSender gets
+  // preventDefaulted or not. Nuke preventDefault on touchmove, rename |uncanceledMoveCausesScroll|.
   debug("-- preventDefault on touchmove, without uncanceledMoveCausesScroll --");
   eventToPreventDefault = "touchmove";
   testSingleDrag(false);