Redefined the bit WebTouchEvent.causesScrollingIfUncanceled.

ui/events/blink/blink_event_util.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // MSVC++ requires this to be set before any other includes to get M_PI.
 #define _USE_MATH_DEFINES
 
 #include "ui/events/blink/blink_event_util.h"
 
 #include <stddef.h>
@@ skipping 161 matching lines @@
     touch.tiltX = touch.tiltY = 0;
   }
 
   return touch;
 }
 
 }  // namespace
 
 blink::WebTouchEvent CreateWebTouchEventFromMotionEvent(
     const MotionEvent& event,
-    bool may_cause_scrolling) {
+    bool moved_beyond_slop_region) {
   static_assert(static_cast<int>(MotionEvent::MAX_TOUCH_POINT_COUNT) ==
                     static_cast<int>(blink::WebTouchEvent::touchesLengthCap),
                 "inconsistent maximum number of active touch points");
 
   blink::WebTouchEvent result;
 
   result.type = ToWebInputEventType(event.GetAction());
   result.cancelable = (result.type != WebInputEvent::TouchCancel);
   result.timeStampSeconds =
-      (event.GetEventTime() - base::TimeTicks()).InSecondsF(),
-  result.causesScrollingIfUncanceled = may_cause_scrolling;
+      (event.GetEventTime() - base::TimeTicks()).InSecondsF();
+  result.movedBeyondSlopRegion = moved_beyond_slop_region;
   result.modifiers = EventFlagsToWebEventModifiers(event.GetFlags());
   DCHECK_NE(event.GetUniqueEventId(), 0U);
   result.uniqueTouchEventId = event.GetUniqueEventId();
   result.touchesLength =
       std::min(static_cast<unsigned>(event.GetPointerCount()),
                static_cast<unsigned>(WebTouchEvent::touchesLengthCap));
   DCHECK_GT(result.touchesLength, 0U);
 
   for (size_t i = 0; i < result.touchesLength; ++i)
     result.touches[i] = CreateWebTouchPoint(event, i);
 
   return result;
 }
 
+bool IsTouchSequenceStart(const MotionEvent& event) {

[tdresser, 2016/02/05 14:19:00]

Isn't this equivalent to event.GetAction() == ACTION_DOWN?

http://developer.android.com/reference/android/view/MotionEvent.html#ACTION_DOWN

[mustaq, 2016/02/05 15:29:18]

Thanks for the catch: I was trying to return true on multi-tap, but my
filtered_gesture_provider logic works as-is with your suggestion.

+  if (ToWebInputEventType(event.GetAction()) != WebInputEvent::TouchStart)
+    return false;
+
+  size_t num_touches = event.GetPointerCount();
+  if (!num_touches)
+    return false;
+
+  for (size_t i = 0; i < num_touches; i++) {
+    if (ToWebTouchPointState(event, i) != WebTouchPoint::StatePressed)
+      return false;
+  }
+
+  return true;
+}
+
 int EventFlagsToWebEventModifiers(int flags) {
   int modifiers = 0;
 
   if (flags & EF_SHIFT_DOWN)
     modifiers |= blink::WebInputEvent::ShiftKey;
   if (flags & EF_CONTROL_DOWN)
     modifiers |= blink::WebInputEvent::ControlKey;
   if (flags & EF_ALT_DOWN)
     modifiers |= blink::WebInputEvent::AltKey;
   if (flags & EF_COMMAND_DOWN)
@@ skipping 247 matching lines @@
 
       // TODO(oshima): Find out if ContextMenu needs to be scaled.
       default:
         break;
     }
   }
   return scaled_event;
 }
 
 }  // namespace ui