Expose native, desktop and mobile gesture detection defaults

Provide generic desktop and mobile gesture configurations, in addition
to the native platform configuration. This will allow devtools touch
emulation to more faithfully emulate a particular device.

Note that this change involved decoupling the TouchEventQueue from
platform-specific slop region constants, afforded by a WebTouchEvent
flag indicating whether the event may cause scrolling as a default
action.

BUG=425586

Review URL: https://codereview.chromium.org/679633005

Cr-Commit-Position: refs/heads/master@{#308429}

2 files changed, 11 insertions, 3 deletions

diff --git a/content/common/input/synthetic_web_input_event_builders.cc b/content/common/input/synthetic_web_input_event_builders.cc
index d3addb6..ab2968a 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);
diff --git a/content/common/input/web_input_event_traits.cc b/content/common/input/web_input_event_traits.cc
index 087cf61..4e9c754 100644
--- a/content/common/input/web_input_event_traits.cc
+++ b/content/common/input/web_input_event_traits.cc
@@ -237,6 +237,7 @@ void Coalesce(const WebTouchEvent& event_to_coalesce, WebTouchEvent* event) {
     if (old_event.touches[i_old].state == blink::WebTouchPoint::StateMoved)
       event->touches[i].state = blink::WebTouchPoint::StateMoved;
   }
+  event->causesScrollingIfUncanceled |= old_event.causesScrollingIfUncanceled;
 }
 
 bool CanCoalesce(const WebGestureEvent& event_to_coalesce,