Process touch events in sorted order.

We are mapping a single QTouchEvent to
multiple MotionEventQt for Chromium.
For gesture recognition it is important
that these motion events are being processed
in a sorted manner, as a move event might
trigger a different gesture depending on
how many ACTION_DOWN or ACTION_POINTER_DOWN
were received before.

It is particularly illegal to process an ACTION_MOVE
with multiple touch points without having received
a ACTION_POINTER_DOWN before.

Change-Id: I75d22dd845774a14b5f590e0e0ce46263c4a49f4
Reviewed-by: Jocelyn Turcotte <jocelyn.turcotte@digia.com>
Reviewed-by: Andras Becsi <andras.becsi@digia.com>

src/core/render_widget_host_view_qt.cpp

@@ -133,6 +133,12 @@ static inline ui::GestureProvider::Config QtGestureProviderConfig() {
     return config;
 }
 
+static inline bool compareTouchPoints(const QTouchEvent::TouchPoint &lhs, const QTouchEvent::TouchPoint &rhs)
+{
+    // TouchPointPressed < TouchPointMoved < TouchPointReleased
+    return lhs.state() < rhs.state();
+}
+
 class MotionEventQt : public ui::MotionEvent {
 public:
     MotionEventQt(const QList<QTouchEvent::TouchPoint> &touchPoints, const base::TimeTicks &eventTime, Action action, int index = -1)
@@ -983,6 +989,10 @@ void RenderWidgetHostViewQt::handleTouchEvent(QTouchEvent *ev)
     if (ev->type() == QEvent::TouchBegin)
         m_sendMotionActionDown = true;
 
+    // Make sure that ACTION_POINTER_DOWN is delivered before ACTION_MOVE,
+    // and ACTION_MOVE before ACTION_POINTER_UP.
+    std::sort(touchPoints.begin(), touchPoints.end(), compareTouchPoints);
+
     for (int i = 0; i < touchPoints.size(); ++i) {
         ui::MotionEvent::Action action;
         switch (touchPoints[i].state()) {