Add slave touch device to touch_device_lookup_ and touch_device_list_

ui/events/devices/x11/touch_factory_x11.cc

Index: ui/events/devices/x11/touch_factory_x11.cc
diff --git a/ui/events/devices/x11/touch_factory_x11.cc b/ui/events/devices/x11/touch_factory_x11.cc
index 3b91724f4f6a6e8ab31489fe58d92aec9648d434..0a1a2f8642487e5cfee0511ffa2254ab55d6c82f 100644
--- a/ui/events/devices/x11/touch_factory_x11.cc
+++ b/ui/events/devices/x11/touch_factory_x11.cc
@@ -125,6 +125,8 @@ void TouchFactory::UpdateDeviceList(XDisplay* display) {
           // Only care direct touch device (such as touch screen) right now
           if (tci->mode == XIDirectTouch) {
             CacheTouchscreenIds(devinfo.deviceid);
+            touch_device_lookup_[devinfo.deviceid] = true;
+            touch_device_list_[devinfo.deviceid] = false;

[sadrul, 2016/12/12 16:02:06]

I think this is getting fairly confusing. Can you merge the two loops (this one,
and the one in line ~102:111)? Because they are beginning to look really
similar.

             if (devinfo.use == XISlavePointer) {
               device_master_id_list_[devinfo.deviceid] = devinfo.attachment;
               // If the slave device is direct touch device, we also set its
@@ -149,6 +151,9 @@ bool TouchFactory::ShouldProcessXI2Event(XEvent* xev) {
   if (event->evtype == XI_TouchBegin ||
       event->evtype == XI_TouchUpdate ||
       event->evtype == XI_TouchEnd) {
+    // TODO(chaopeng) we need to add deviceid to touch_device_lookup_ if this
+    // assertion failed.
+    DCHECK(touch_device_lookup_[xiev->deviceid]);
     // Since SetupXI2ForXWindow() selects events from all devices, for a
     // touchscreen attached to a master pointer device, X11 sends two
     // events for each touch: one from the slave (deviceid == the id of