TouchpadInputMapper: report usage metrics

Bug: 280604085
Test: touch touchpad with fingers and palm, make some gestures, then
      check metrics reported through statsd_testdrive for atom 10191
Change-Id: Ie7985cdfa628c63514aa1264287eb83dbfbd7625
diff --git a/services/inputflinger/InputDeviceMetricsCollector.cpp b/services/inputflinger/InputDeviceMetricsCollector.cpp
index 3e25cc3..c21a4f2 100644
--- a/services/inputflinger/InputDeviceMetricsCollector.cpp
+++ b/services/inputflinger/InputDeviceMetricsCollector.cpp
@@ -39,6 +39,9 @@
 const bool DEBUG = __android_log_is_loggable(ANDROID_LOG_DEBUG, LOG_TAG, ANDROID_LOG_INFO);
 
 int32_t linuxBusToInputDeviceBusEnum(int32_t linuxBus) {
+    // When adding cases to this switch, also add them to the copy of this method in
+    // TouchpadInputMapper.cpp.
+    // TODO(b/286394420): deduplicate this method with the one in TouchpadInputMapper.cpp.
     switch (linuxBus) {
         case BUS_USB:
             return util::INPUT_DEVICE_USAGE_REPORTED__DEVICE_BUS__USB;