Remove unused gesture preview trail code

public final class GestureStrokeWithPreviewPoints extends GestureStroke {

    public static final int PREVIEW_CAPACITY = 256;

    private static final boolean ENABLE_INTERPOLATION = true;

    private final ResizableIntArray mPreviewEventTimes = new ResizableIntArray(PREVIEW_CAPACITY);

    private final ResizableIntArray mPreviewXCoordinates = new ResizableIntArray(PREVIEW_CAPACITY);

    private final ResizableIntArray mPreviewYCoordinates = new ResizableIntArray(PREVIEW_CAPACITY);

    private final HermiteInterpolator mInterpolator = new HermiteInterpolator();

    private int mLastInterpolatedPreviewIndex;

    private int mMinPreviewSamplingDistanceSquared;

    private int mLastX;

    private int mLastY;

    private double mMinPreviewSamplingDistance;

    private double mDistanceFromLastSample;

    // TODO: Move these constants to resource.

    // The minimum linear distance between sample points for preview in keyWidth unit.

    private static final float MIN_PREVIEW_SAMPLING_RATIO_TO_KEY_WIDTH = 0.1f;

    // The minimum trail distance between sample points for preview in keyWidth unit when using

    // interpolation.

    private static final float MIN_PREVIEW_SAMPLING_RATIO_TO_KEY_WIDTH_WITH_INTERPOLATION = 0.2f;

    private static final float MIN_PREVIEW_SAMPLING_RATIO_TO_KEY_WIDTH = 0.2f;

    // The angular threshold to use interpolation in radian. PI/12 is 15 degree.

    private static final double INTERPOLATION_ANGULAR_THRESHOLD = Math.PI / 12.0d;

    private static final int MAX_INTERPOLATION_PARTITION = 4;

    @Override

    public void setKeyboardGeometry(final int keyWidth, final int keyboardHeight) {

        super.setKeyboardGeometry(keyWidth, keyboardHeight);

        final float samplingRatioToKeyWidth = ENABLE_INTERPOLATION

                ? MIN_PREVIEW_SAMPLING_RATIO_TO_KEY_WIDTH_WITH_INTERPOLATION

                : MIN_PREVIEW_SAMPLING_RATIO_TO_KEY_WIDTH;

        final float samplingRatioToKeyWidth = MIN_PREVIEW_SAMPLING_RATIO_TO_KEY_WIDTH;

        mMinPreviewSamplingDistance = keyWidth * samplingRatioToKeyWidth;

        mMinPreviewSamplingDistanceSquared = (int)(

                mMinPreviewSamplingDistance * mMinPreviewSamplingDistance);

    }

    private boolean needsSampling(final int x, final int y, final boolean isMajorEvent) {

        if (ENABLE_INTERPOLATION) {

        mDistanceFromLastSample += Math.hypot(x - mLastX, y - mLastY);

        mLastX = x;

        mLastY = y;

        return false;

    }

        final int dx = x - mLastX;

        final int dy = y - mLastY;

        if (isMajorEvent || dx * dx + dy * dy >= mMinPreviewSamplingDistanceSquared) {

            mLastX = x;

            mLastY = y;

            return true;

        }

        return false;

    }

    @Override

    public boolean addPointOnKeyboard(final int x, final int y, final int time,

            final boolean isMajorEvent) {

    public int interpolateStrokeAndReturnStartIndexOfLastSegment(final int lastInterpolatedIndex,

            final ResizableIntArray eventTimes, final ResizableIntArray xCoords,

            final ResizableIntArray yCoords) {

        if (!ENABLE_INTERPOLATION) {

            return lastInterpolatedIndex;

        }

        final int size = mPreviewEventTimes.getLength();

        final int[] pt = mPreviewEventTimes.getPrimitiveArray();

        final int[] px = mPreviewXCoordinates.getPrimitiveArray();