Make sure send one WebTouchEvent ack per ui::TouchEvent

content/browser/renderer_host/render_widget_host_view_aura.cc

Index: content/browser/renderer_host/render_widget_host_view_aura.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.cc b/content/browser/renderer_host/render_widget_host_view_aura.cc
index fd85fcc8745cdf59c93e87322518bda129aff961..e9fcf673898ea5d9680a15e12da4250af03d6813 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -805,6 +805,18 @@ void RenderWidgetHostViewAura::ParentHierarchyChanged() {
   HandleParentBoundsChanged();
 }
 
+void RenderWidgetHostViewAura::SetTouchPointStateStationary(

[jdduke (slow), 2015/05/07 15:20:28]

Hmm, ideally this would just be a free, nonmember function, see my comments in
the test. Maybe call this |MarkUnchangedTouchPointsAsStationary()|?

[lanwei, 2015/05/08 02:12:32]

Because I need to use this function in the unittest, so have to make it as a
member function.

[jdduke (slow), 2015/05/08 02:20:32]

Yeah, noticed that later, let's see what Tim says about needing to do the touch
bookkeeping.

+    blink::WebTouchEvent* event,
+    int touch_id) {

[jdduke (slow), 2015/05/07 15:20:28]

Maybe |changed_touch_id|?

[lanwei, 2015/05/08 02:12:32]

Done.

+  if (event->type == blink::WebInputEvent::TouchMove ||
+      event->type == blink::WebInputEvent::TouchCancel) {
+    for (size_t i = 0; i < event->touchesLength; ++i) {
+      if (event->touches[i].id != touch_id)
+        event->touches[i].state = blink::WebTouchPoint::StateStationary;
+    }
+  }
+}
+
 void RenderWidgetHostViewAura::MovePluginWindows(
     const std::vector<WebPluginGeometry>& plugin_window_moves) {
 #if defined(OS_WIN)
@@ -2184,6 +2196,10 @@ void RenderWidgetHostViewAura::OnTouchEvent(ui::TouchEvent* event) {
   // processed by the gesture recognizer before events currently awaiting
   // dispatch in the touch queue.
   event->DisableSynchronousHandling();
+
+  // Set unchange touch point to StateStationary for touchmove and
+  // touchcancel to make sure only send one ack per WebTouchEvent.
+  SetTouchPointStateStationary(&touch_event, event->touch_id());
   host_->ForwardTouchEventWithLatencyInfo(touch_event, *event->latency());
 }