message: HCM: save 8 or 16 bytes for each http filter
  Use bit field and adjust member order.
diff: @@ -96,9 +96,9 @@ private:
  */
  struct ActiveStreamFilterBase : public virtual StreamFilterCallbacks {
  ActiveStreamFilterBase(ActiveStream& parent, bool dual_filter)
  - : iteration_state_(IterationState::Continue), iterate_from_current_filter_(false),
  - parent_(parent), headers_continued_(false), continue_headers_continued_(false),
  - end_stream_(false), dual_filter_(dual_filter) {}
  + : parent_(parent), iteration_state_(IterationState::Continue),
  + iterate_from_current_filter_(false), headers_continued_(false),
  + continue_headers_continued_(false), end_stream_(false), dual_filter_(dual_filter) {}
  // Functions in the following block are called after the filter finishes processing
  // corresponding data. Those functions handle state updates and data storage (if needed)
  @@ -159,13 +159,13 @@ private:
  StopAllWatermark, // Iteration has stopped for all frame types, and following data should
  // be buffered until high watermark is reached.
  };
  + ActiveStream& parent_;
  IterationState iteration_state_;
  // If the filter resumes iteration from a StopAllBuffer/Watermark state, the current filter
  // hasn't parsed data and trailers. As a result, the filter iteration should start with the
  // current filter instead of the next one. If true, filter iteration starts with the current
  // filter. Otherwise, starts with the next filter in the chain.
  - bool iterate_from_current_filter_;
  - ActiveStream& parent_;
  + bool iterate_from_current_filter_ : 1;
  bool headers_continued_ : 1;
  bool continue_headers_continued_ : 1;
  // If true, end_stream is called for this filter.
  