@Override protected void onLayout(boolean changed, int l, int t, int r, int b) {
    if (mPager != null) {
      final float offset = mLastKnownPositionOffset >= 0 ? mLastKnownPositionOffset : 0;
      updateTextPositions(mLastKnownCurrentPage, offset, true);
    }
  }
Set the {@link Gravity} used to position text within the title strip.
Only the vertical gravity component is used.

@param gravity {@link Gravity} constant for positioning title text
sample/src/main/java/android/support/v4/view/PagerTitleStripV22.java