Fix SafeAdd and SafeMultiply

BUG=145648,145544


Review URL: https://chromiumcodereview.appspot.com/10916165

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@155478 0039d316-1c4b-4281-b951-d872f2087c98
  bool ShouldDeferDraws() {
    return !offscreen_target_frame_buffer_.get() &&
           bound_draw_framebuffer_ == NULL &&
           surface_->DeferDraws();
  }

  bool ShouldDeferDraws() {
    return !offscreen_target_frame_buffer_.get() &&
           bound_draw_framebuffer_ == NULL &&
           surface_->DeferDraws();
  }
