code: private void updateTitle(int selected) {
          if (mActionMode != null) {
              if (mTitleProvider != null)
                  mActionMode.setTitle(mTitleProvider.getTitle(selected));
              else
                  mActionMode.setTitle(String.valueOf(selected));
          }
      }
docs: updates the title to reflect the current selected items or to show a user defined title
  
  @param selected number of selected items