ozone: Map TouchEvent::touch_id_ into expected range

ui/events/ozone/evdev/touch_event_converter_evdev_unittest.cc

Index: ui/events/ozone/evdev/touch_event_converter_evdev_unittest.cc
diff --git a/ui/events/ozone/evdev/touch_event_converter_evdev_unittest.cc b/ui/events/ozone/evdev/touch_event_converter_evdev_unittest.cc
index e2bc3a4d7010735a797ac362f8d1683b98b9cc4e..cc30bf6cc847e006e38aa0e379b1a50b70f14213 100644
--- a/ui/events/ozone/evdev/touch_event_converter_evdev_unittest.cc
+++ b/ui/events/ozone/evdev/touch_event_converter_evdev_unittest.cc
@@ -563,6 +563,46 @@ TEST_F(TouchEventConverterEvdevTest, CheckSlotLimit) {
   EXPECT_EQ(1u, size());
 }
 
+// crbug.com/472308
+TEST_F(TouchEventConverterEvdevTest, TestTouchIdOffset) {
+  ui::MockTouchEventConverterEvdev* dev = device();
+  InitPixelTouchscreen(dev);
+
+  const int kTouchIdOffset = 20;
+  dev->SetTouchIdOffset(kTouchIdOffset);
+
+  struct input_event mock_kernel_queue[] = {
+      {{0, 0}, EV_ABS, ABS_MT_SLOT, 0},
+      {{0, 0}, EV_ABS, ABS_MT_TRACKING_ID, 100},
+      {{0, 0}, EV_ABS, ABS_MT_POSITION_X, 999},
+      {{0, 0}, EV_ABS, ABS_MT_POSITION_Y, 888},
+      {{0, 0}, EV_ABS, ABS_MT_PRESSURE, 55},
+      {{0, 0}, EV_ABS, ABS_MT_SLOT, 1},
+      {{0, 0}, EV_ABS, ABS_MT_TRACKING_ID, 200},
+      {{0, 0}, EV_ABS, ABS_MT_PRESSURE, 44},
+      {{0, 0}, EV_ABS, ABS_MT_POSITION_X, 777},
+      {{0, 0}, EV_ABS, ABS_MT_POSITION_Y, 666},
+      {{0, 0}, EV_ABS, ABS_X, 999},
+      {{0, 0}, EV_ABS, ABS_Y, 888},
+      {{0, 0}, EV_ABS, ABS_PRESSURE, 55},
+      {{0, 0}, EV_SYN, SYN_REPORT, 0},
+  };
+
+  // Check that two events are generated.
+  dev->ConfigureReadMock(mock_kernel_queue, arraysize(mock_kernel_queue), 0);
+  dev->ReadNow();
+
+  const unsigned int kExpectedEventCount = 2;
+  EXPECT_EQ(kExpectedEventCount, size());
+  if (kExpectedEventCount != size())
+    return;
+
+  ui::TouchEventParams ev0 = dispatched_event(0);
+  ui::TouchEventParams ev1 = dispatched_event(1);
+  EXPECT_EQ(ev0.touch_id, kTouchIdOffset + 0);
+  EXPECT_EQ(ev1.touch_id, kTouchIdOffset + 1);
+}
+
 namespace {
 
 // TouchNoiseFilter which: