e
  * Chrome userfriendly titles & values are an object that shows the total
  * wall clock time spent in |rangeOfInterest|, and the list of event
  * labels of the group and their total wall clock time in |rangeOfInterest|.
  *
  * Example:
  *   {
  *     layout: {
  *         total: 100,
  *         events: {'FrameView::performPreLayoutTasks': 20,..}},
  *     v8_runtime: {
  *         total: 500,
  *         events: {'String::NewExternalTwoByte': 0.5,..}},
  *     ...
  *   }
  */
  function generateWal