Ensure Multi-finger tap generates both GestureScrollBegin and GestureScrollEnd.

ui/events/gestures/gesture_sequence.cc

Index: ui/events/gestures/gesture_sequence.cc
diff --git a/ui/events/gestures/gesture_sequence.cc b/ui/events/gestures/gesture_sequence.cc
index 5ee5d5e53fbe6204b204c0755773fd60bf4fbd1c..6b77ad246daafc1bb20242b91a5d9b5115beb3d3 100644
--- a/ui/events/gestures/gesture_sequence.cc
+++ b/ui/events/gestures/gesture_sequence.cc
@@ -633,6 +633,9 @@ GestureSequence::Gestures* GestureSequence::ProcessTouchEventForGesture(
     case GST_PENDING_TWO_FINGER_TAP_FIRST_RELEASED:
     case GST_PENDING_TWO_FINGER_TAP_SECOND_RELEASED:
       TwoFingerTouchReleased(event, point, gestures.get());
+      AppendScrollGestureBegin(
+          point, point.first_touch_position(), gestures.get());
+      scroll_type_ = ST_FREE;
       set_state(GS_SCROLL);

[sadrul, 2014/03/10 03:54:52]

It may make sense to have a 'TransitionToScrollState()' for these 4 lines.

[tdresser, 2014/03/10 12:36:39]

Done. Named "StartRailFreeScroll," to indicate that it doesn't merely perform a
state change.

       break;
     case GST_PENDING_TWO_FINGER_TAP_FIRST_MOVED:
@@ -648,6 +651,8 @@ GestureSequence::Gestures* GestureSequence::ProcessTouchEventForGesture(
     case GST_PENDING_TWO_FINGER_TAP_SECOND_RELEASED_HANDLED:
     case GST_PENDING_TWO_FINGER_TAP_FIRST_CANCELLED:
     case GST_PENDING_TWO_FINGER_TAP_SECOND_CANCELLED:
+      AppendScrollGestureBegin(
+          point, point.first_touch_position(), gestures.get());
       scroll_type_ = ST_FREE;
       set_state(GS_SCROLL);
       break;
@@ -661,16 +666,20 @@ GestureSequence::Gestures* GestureSequence::ProcessTouchEventForGesture(
     case GST_PENDING_TWO_FINGER_TAP_NO_PINCH_FIRST_RELEASED:
     case GST_PENDING_TWO_FINGER_TAP_NO_PINCH_SECOND_RELEASED:
       TwoFingerTouchReleased(event, point, gestures.get());
-      // We transit into GS_SCROLL even though the touch move can be
-      // consumed and no scroll should happen. crbug.com/240399.
+      // We transition into GS_SCROLL even though the touch move can be consumed
+      // and no scroll should happen. crbug.com/240399.
+      AppendScrollGestureBegin(
+          point, point.first_touch_position(), gestures.get());
       set_state(GS_SCROLL);
       break;
     case GST_PENDING_TWO_FINGER_TAP_NO_PINCH_FIRST_RELEASED_HANDLED:
     case GST_PENDING_TWO_FINGER_TAP_NO_PINCH_SECOND_RELEASED_HANDLED:
     case GST_PENDING_TWO_FINGER_TAP_NO_PINCH_FIRST_CANCELLED:
     case GST_PENDING_TWO_FINGER_TAP_NO_PINCH_SECOND_CANCELLED:
-      // We transit into GS_SCROLL even though the touch move can be
-      // consumed and no scroll should happen. crbug.com/240399.
+      // We transition into GS_SCROLL even though the touch move can be consumed
+      // and no scroll should happen. crbug.com/240399.
+      AppendScrollGestureBegin(
+          point, point.first_touch_position(), gestures.get());
       scroll_type_ = ST_FREE;
       set_state(GS_SCROLL);
       break;
@@ -687,8 +696,10 @@ GestureSequence::Gestures* GestureSequence::ProcessTouchEventForGesture(
     case GST_PENDING_PINCH_SECOND_RELEASED:
     case GST_PENDING_PINCH_FIRST_CANCELLED:
     case GST_PENDING_PINCH_SECOND_CANCELLED:
-      // We transit into GS_SCROLL even though the touch move can be
-      // consumed and no scroll should happen. crbug.com/240399.
+      // We transition into GS_SCROLL even though the touch move can be consumed
+      // and no scroll should happen. crbug.com/240399.
+      AppendScrollGestureBegin(
+          point, point.first_touch_position(), gestures.get());
       scroll_type_ = ST_FREE;
       set_state(GS_SCROLL);
       break;
@@ -700,8 +711,10 @@ GestureSequence::Gestures* GestureSequence::ProcessTouchEventForGesture(
     case GST_PENDING_PINCH_NO_PINCH_SECOND_RELEASED:
     case GST_PENDING_PINCH_NO_PINCH_FIRST_CANCELLED:
     case GST_PENDING_PINCH_NO_PINCH_SECOND_CANCELLED:
-      // We transit into GS_SCROLL even though the touch move can be
-      // consumed and no scroll should happen. crbug.com/240399.
+      // We transition into GS_SCROLL even though the touch move can be consumed
+      // and no scroll should happen. crbug.com/240399.
+      AppendScrollGestureBegin(
+          point, point.first_touch_position(), gestures.get());
       scroll_type_ = ST_FREE;
       set_state(GS_SCROLL);
       break;