Reland of [Ozone] Properly initialize multitouch slot values

ui/events/ozone/evdev/event_device_info.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_EVENTS_OZONE_EVDEV_EVENT_DEVICE_INFO_H_
 #define UI_EVENTS_OZONE_EVDEV_EVENT_DEVICE_INFO_H_
 
 #include <limits.h>
 #include <linux/input.h>
 
+#include <vector>
+
 #include "base/basictypes.h"
 #include "ui/events/ozone/evdev/event_device_util.h"
 #include "ui/events/ozone/evdev/events_ozone_evdev_export.h"
 
+// ABS_MT_SLOT isn't valid options for EVIOCGMTSLOTS ioctl.
+#define EVDEV_ABS_MT_COUNT (ABS_MAX - ABS_MT_SLOT - 1)
+
 namespace ui {
 
 // Device information for Linux input devices
 //
 // This stores and queries information about input devices; in
 // particular it knows which events the device can generate.
 class EVENTS_OZONE_EVDEV_EXPORT EventDeviceInfo {
  public:
   EventDeviceInfo();
   ~EventDeviceInfo();
 
   // Initialize device information from an open device.
   bool Initialize(int fd);
 
   // Check events this device can generate.
   bool HasEventType(unsigned int type) const;
   bool HasKeyEvent(unsigned int code) const;
   bool HasRelEvent(unsigned int code) const;
   bool HasAbsEvent(unsigned int code) const;
   bool HasMscEvent(unsigned int code) const;
   bool HasSwEvent(unsigned int code) const;
   bool HasLedEvent(unsigned int code) const;
 
   // Properties of absolute axes.
   int32 GetAbsMinimum(unsigned int code) const;
   int32 GetAbsMaximum(unsigned int code) const;
+  int32 GetSlotValue(unsigned int code, unsigned int slot) const;
 
   // Check input device properties.
   bool HasProp(unsigned int code) const;
 
   // Has absolute X & Y axes.
   bool HasAbsXY() const;
 
   // Has relativeX & Y axes.
   bool HasRelXY() const;
 
   // Determine whether absolute device X/Y coordinates are mapped onto the
   // screen. This is the case for touchscreens and tablets but not touchpads.
   bool IsMappedToScreen() const;
 
  private:
+  // Return the slot vector in |slot_values_| for |code|.
+  const std::vector<int32_t>& GetMtSlotsForCode(int code) const;
+
   unsigned long ev_bits_[EVDEV_BITS_TO_LONGS(EV_CNT)];
   unsigned long key_bits_[EVDEV_BITS_TO_LONGS(KEY_CNT)];
   unsigned long rel_bits_[EVDEV_BITS_TO_LONGS(REL_CNT)];
   unsigned long abs_bits_[EVDEV_BITS_TO_LONGS(ABS_CNT)];
   unsigned long msc_bits_[EVDEV_BITS_TO_LONGS(MSC_CNT)];
   unsigned long sw_bits_[EVDEV_BITS_TO_LONGS(SW_CNT)];
   unsigned long led_bits_[EVDEV_BITS_TO_LONGS(LED_CNT)];
   unsigned long prop_bits_[EVDEV_BITS_TO_LONGS(INPUT_PROP_CNT)];
 
   struct input_absinfo abs_info_[ABS_CNT];
 
+  // Store the values for the multi-touch properties for each slot.
+  std::vector<int32_t> slot_values_[EVDEV_ABS_MT_COUNT];
+
   DISALLOW_COPY_AND_ASSIGN(EventDeviceInfo);
 };
 
 }  // namspace ui
 
 #endif  // UI_EVENTS_OZONE_EVDEV_EVENT_DEVICE_INFO_H_