Fix touch screen on Linux with or without flag --touch-devices

Using flag --touch-devices=device id or not using it, touch screen should work on Linux,
but now only the touch screens with the ids after the this flag will be set as
touch screens, and we only use touch inputs from master pointer not from the
slave devices, so we are only receiving touch inputs if we set touch-devices equal to
the master pointer id.

BUG=486492

Review URL: https://codereview.chromium.org/1186833005

Cr-Commit-Position: refs/heads/master@{#335785}

2 files changed, 20 insertions, 5 deletions

diff --git a/ui/events/devices/x11/touch_factory_x11.cc b/ui/events/devices/x11/touch_factory_x11.cc
index a971b10..bd7b157 100644
--- a/ui/events/devices/x11/touch_factory_x11.cc
+++ b/ui/events/devices/x11/touch_factory_x11.cc
@@ -130,6 +130,13 @@ void TouchFactory::UpdateDeviceList(Display* display) {
           // Only care direct touch device (such as touch screen) right now
           if (tci->mode == XIDirectTouch)
             CacheTouchscreenIds(devinfo.deviceid);
+            if (devinfo.use == XISlavePointer) {
+              device_master_id_list_[devinfo.deviceid] = devinfo.attachment;
+              // If the slave device is direct touch device, we also set its
+              // master device to be touch device.
+              touch_device_lookup_[devinfo.attachment] = true;
+              touch_device_list_[devinfo.attachment] = true;
+            }
         }
       }
     }
@@ -219,11 +226,16 @@ void TouchFactory::SetupXI2ForXWindow(Window window) {
 void TouchFactory::SetTouchDeviceList(const std::vector<int>& devices) {
   touch_device_lookup_.reset();
   touch_device_list_.clear();
-  for (std::vector<int>::const_iterator iter = devices.begin();
-       iter != devices.end(); ++iter) {
-    DCHECK(IsValidDevice(*iter));
-    touch_device_lookup_[*iter] = true;
-    touch_device_list_[*iter] = false;
+  for (int deviceid : devices) {
+    DCHECK(IsValidDevice(deviceid));
+    touch_device_lookup_[deviceid] = true;
+    touch_device_list_[deviceid] = false;
+    if (device_master_id_list_.find(deviceid) != device_master_id_list_.end()) {
+      // When we set the device through the "--touch-devices" flag to slave
+      // touch device, we also set its master device to be touch device.
+      touch_device_lookup_[device_master_id_list_[deviceid]] = true;
+      touch_device_list_[device_master_id_list_[deviceid]] = false;
+    }
   }
 }
 
diff --git a/ui/events/devices/x11/touch_factory_x11.h b/ui/events/devices/x11/touch_factory_x11.h
index 43174a7..c2e9580 100644
--- a/ui/events/devices/x11/touch_factory_x11.h
+++ b/ui/events/devices/x11/touch_factory_x11.h
@@ -134,6 +134,9 @@ class EVENTS_DEVICES_EXPORT TouchFactory {
 
   SequentialIDGenerator id_generator_;
 
+  // Associate each device ID with its master device ID.
+  std::map<int, int> device_master_id_list_;
+
   DISALLOW_COPY_AND_ASSIGN(TouchFactory);
 };