Expose native, desktop and mobile gesture detection defaults

content/common/input/synthetic_web_input_event_builders.cc

Index: content/common/input/synthetic_web_input_event_builders.cc
diff --git a/content/common/input/synthetic_web_input_event_builders.cc b/content/common/input/synthetic_web_input_event_builders.cc
index d3addb67918cc46a16e8e14ec3124a9db9aa6f88..ab2968a771558559bfede191c77217f6ea4e5c78 100644
--- a/content/common/input/synthetic_web_input_event_builders.cc
+++ b/content/common/input/synthetic_web_input_event_builders.cc
@@ -163,6 +163,7 @@ void SyntheticWebTouchEvent::ResetPoints() {
   }
   touchesLength = point;
   type = WebInputEvent::Undefined;
+  causesScrollingIfUncanceled = false;
 }
 
 int SyntheticWebTouchEvent::PressPoint(float x, float y) {
@@ -181,7 +182,11 @@ int SyntheticWebTouchEvent::PressPoint(float x, float y) {
 }
 
 void SyntheticWebTouchEvent::MovePoint(int index, float x, float y) {
-  CHECK(index >= 0 && index < touchesLengthCap);
+  CHECK_GE(index, 0);
+  CHECK_LT(index, touchesLengthCap);
+  // Always set this bit to avoid otherwise unexpected touchmove suppression.
+  // The caller can opt-out explicitly, if necessary.
+  causesScrollingIfUncanceled = true;
   WebTouchPoint& point = touches[index];
   point.position.x = point.screenPosition.x = x;
   point.position.y = point.screenPosition.y = y;
@@ -191,14 +196,16 @@ void SyntheticWebTouchEvent::MovePoint(int index, float x, float y) {
 }
 
 void SyntheticWebTouchEvent::ReleasePoint(int index) {
-  CHECK(index >= 0 && index < touchesLengthCap);
+  CHECK_GE(index, 0);
+  CHECK_LT(index, touchesLengthCap);
   touches[index].state = WebTouchPoint::StateReleased;
   WebTouchEventTraits::ResetType(
       WebInputEvent::TouchEnd, timeStampSeconds, this);
 }
 
 void SyntheticWebTouchEvent::CancelPoint(int index) {
-  CHECK(index >= 0 && index < touchesLengthCap);
+  CHECK_GE(index, 0);
+  CHECK_LT(index, touchesLengthCap);
   touches[index].state = WebTouchPoint::StateCancelled;
   WebTouchEventTraits::ResetType(
       WebInputEvent::TouchCancel, timeStampSeconds, this);