touchui: Convert XI2 MT tracking id to slot id for gesture recognizer

views/events/event_x.cc

Index: views/events/event_x.cc
diff --git a/views/events/event_x.cc b/views/events/event_x.cc
index 31300551fad4ff6fc7e14c160bc09b8983ebfccf..1bcc20b297c6fcde94458a560c5dd7007159718f 100644
--- a/views/events/event_x.cc
+++ b/views/events/event_x.cc
@@ -124,16 +124,20 @@ ui::EventType GetTouchEventType(XEvent* xev) {
 int GetTouchIDFromXEvent(XEvent* xev) {
   float id = 0;
 #if defined(USE_XI2_MT)
-  // TODO(ningxin.hu@gmail.com): Make the id always start from 0 for a new
-  // touch-sequence when TRACKING_ID is used to extract the touch id.
-  TouchFactory::TouchParam tp = TouchFactory::TP_TRACKING_ID;
+  float tracking_id;
+  TouchFactory* factory = TouchFactory::GetInstance();
+  if (factory->ExtractTouchParam(
+          *xev, TouchFactory::TP_TRACKING_ID, &tracking_id))

[sadrul, 2011/09/19 16:13:36]

4-space indent here and in line 137

[ningxin.hu, 2011/09/20 16:08:49]

Will fix. Thanks.

+    id = factory->AllocateSlotIdForTrackingId(tracking_id);
+  else
+    LOG(ERROR) << "Could not get the touch ID for the event. Using 0.";
+  return id;
 #else
-  TouchFactory::TouchParam tp = TouchFactory::TP_SLOT_ID;
-#endif
   if (!TouchFactory::GetInstance()->ExtractTouchParam(
-          *xev, tp, &id))
+          *xev, TouchFactory::TP_SLOT_ID, &id))
     LOG(ERROR) << "Could not get the touch ID for the event. Using 0.";
   return id;
+#endif
 }
 
 ui::EventType EventTypeFromNative(NativeEvent2 native_event) {
@@ -424,7 +428,17 @@ TouchEvent::TouchEvent(NativeEvent2 native_event_2,
                                               TouchFactory::TP_ORIENTATION,
                                               0.0)),
       force_(GetTouchForceFromXEvent(native_event_2)) {
-#if !defined(USE_XI2_MT)
+#if defined(USE_XI2_MT)
+  if (type() == ui::ET_TOUCH_RELEASED) {
+    TouchFactory* factory = TouchFactory::GetInstance();

[sadrul, 2011/09/19 16:13:36]

Please add a NOTE here explaining that for PRESSED events, the touch-id gets
allocated by TouchFactory.

[ningxin.hu, 2011/09/20 16:08:49]

Will do that. Thanks.

+    float tracking_id;
+    if (factory->ExtractTouchParam(*native_event_2,
+                                   TouchFactory::TP_TRACKING_ID,
+                                   &tracking_id)) {
+      factory->ReleaseSlotIdForTrackingId(tracking_id);
+    }
+  }
+#else
   if (type() == ui::ET_TOUCH_PRESSED || type() == ui::ET_TOUCH_RELEASED) {
     TouchFactory* factory = TouchFactory::GetInstance();
     float slot;