Port Chromium OS touch noise filtering to Chromium

ui/events/ozone/evdev/touch_noise/single_position_touch_noise_filter.h

Index: ui/events/ozone/evdev/touch_noise/single_position_touch_noise_filter.h
diff --git a/ui/events/ozone/evdev/touch_noise/single_position_touch_noise_filter.h b/ui/events/ozone/evdev/touch_noise/single_position_touch_noise_filter.h
new file mode 100644
index 0000000000000000000000000000000000000000..16457cb74fde208c40ffab6981387e23c34fb779
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+++ b/ui/events/ozone/evdev/touch_noise/single_position_touch_noise_filter.h
@@ -0,0 +1,51 @@
+// Copyright 2015 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_SINGLE_POSITION_TOUCH_NOISE_FILTER_H_
+#define UI_EVENTS_OZONE_EVDEV_SINGLE_POSITION_TOUCH_NOISE_FILTER_H_
+
+#include "base/macros.h"
+#include "base/time/time.h"
+#include "ui/events/ozone/evdev/touch_noise/touch_noise_filter.h"
+#include "ui/gfx/geometry/point_f.h"
+
+namespace ui {
+
+class SinglePositionTouchNoiseFilter : public TouchNoiseFilter {
+ public:
+  SinglePositionTouchNoiseFilter();
+  ~SinglePositionTouchNoiseFilter() override {}
+
+  // TouchNoiseFilter:
+  void FilterFrame(Frame* previous, Frame* next) override;
+
+ private:
+  struct Touch {
+    Touch();
+    ~Touch();
+
+    bool valid;
+    gfx::PointF location;
+    size_t slot;
+    base::TimeDelta begin;
+    base::TimeDelta end;
+  };
+
+  void StopTrackingTouch(size_t index);
+  void TrackTouch(size_t slot, Frame* frame);
+
+  // A mapping of slot to tracked touch index in |tracked_touches_|.
+  size_t tracked_slots_[kNumSlots];
+
+  // A circular buffer of tracked touches [|touches_start_|, |touches_end_|).
+  static const int kNumTrackedTouches = 100;
+  Touch tracked_touches_[kNumTrackedTouches];
+
+  size_t touches_start_;
+  size_t touches_end_;
+};
+
+}  // namespace touch_noise_filter
+
+#endif  // SINGLE_POSITION_FILTER_H__