ozone: evdev: Add gamepad support

ui/events/ozone/evdev/event_device_info.cc

Index: ui/events/ozone/evdev/event_device_info.cc
diff --git a/ui/events/ozone/evdev/event_device_info.cc b/ui/events/ozone/evdev/event_device_info.cc
index aa877e0b18ae4f955bec42af2fbf167bef1841dc..40f8f90a5544c55ffc57057ebd65a313be72609c 100644
--- a/ui/events/ozone/evdev/event_device_info.cc
+++ b/ui/events/ozone/evdev/event_device_info.cc
@@ -251,6 +251,11 @@ void EventDeviceInfo::SetDeviceType(InputDeviceType type) {
   device_type_ = type;
 }
 
+void EventDeviceInfo::SetId(uint16_t vendor_id, uint16_t product_id) {
+  vendor_id_ = vendor_id;
+  product_id_ = product_id;
+}
+
 bool EventDeviceInfo::HasEventType(unsigned int type) const {
   if (type > EV_MAX)
     return false;
@@ -427,6 +432,21 @@ bool EventDeviceInfo::HasTouchscreen() const {
   return HasAbsXY() && HasDirect();
 }
 
+bool EventDeviceInfo::HasGamepad() const {
+  if (!HasEventType(EV_KEY))
+    return false;
+
+  // If the device has gamepad button, it will be considered
+  // as a gamepad. Note: this WILL have false positives and false negatives. A

[scottmg, 2017/05/01 18:20:51]

"it will be considered to be a gamepad."

[jkwang, 2017/05/01 22:21:56]

Done.

+  // concrete solution will use ID_INPUT_JOYSTICK with some patch removing false

[scottmg, 2017/05/01 18:20:51]

I don't know anything about Ozone (in fact I can't even find the headers for it)
but can we do this now instead of an incorrect test?

[jkwang, 2017/05/01 22:21:56]

ID_INPUT_JOYSTICK itself has false positives. There are some udev patches like
this one: https://github.com/denilsonsa/udev-joystick-blacklist. Most of the
false positives are "multi media keyboard" or "wacom tablet".

+  // positives.
+  for (int key = BTN_JOYSTICK; key <= BTN_THUMBR; ++key)
+    if (HasKeyEvent(key))
+      return true;
+
+  return false;
+}
+
 EventDeviceInfo::LegacyAbsoluteDeviceType
 EventDeviceInfo::ProbeLegacyAbsoluteDevice() const {
   if (!HasAbsXY())